diff --git a/lib/in-memory-report.js b/lib/in-memory-report.js
index 9b30420..2ab8533 100644
--- a/lib/in-memory-report.js
+++ b/lib/in-memory-report.js
@@ -1,5 +1,8 @@
-class InMemoryReport {
+const { ReportBase } = require('istanbul-lib-report')
+
+class InMemoryReport extends ReportBase {
   constructor (opt) {
+    super(opt)
     this.opt = opt
   }
 
diff --git a/lib/reporter.js b/lib/reporter.js
index 6d982bd..135d8ce 100644
--- a/lib/reporter.js
+++ b/lib/reporter.js
@@ -218,11 +218,11 @@ var CoverageReporter = function (rootConfig, helper, logger, emitter) {
     coverageMap.merge(result.coverage)
   }
 
-  this.onRunComplete = function (browsers, results) {
+  this.onRunComplete = async function (browsers, results) {
     const checkedCoverage = {}
 
     for (const reporterConfig of reporters) {
-      browsers.forEach(function (browser) {
+      await Promise.all(browsers.map(async (browser) => {
         const coverageMap = coverageMaps[browser.id]
         if (!coverageMap) {
           return
@@ -231,14 +231,15 @@ var CoverageReporter = function (rootConfig, helper, logger, emitter) {
         const mainDir = reporterConfig.dir || config.dir
         const subDir = reporterConfig.subdir || config.subdir
         const outputPath = generateOutputPath(basePath, browser.name, mainDir, subDir)
+        const remappedCoverageMap = await sourceMapStore.transformCoverage(coverageMap)
 
         const options = helper.merge(config, reporterConfig, {
           dir: outputPath,
           subdir: '',
           browser: browser,
-          emitter: emitter
+          emitter: emitter,
+          coverageMap: remappedCoverageMap
         })
-        const remappedCoverageMap = sourceMapStore.transformCoverage(coverageMap).map
 
         // If config.check is defined, check coverage levels for each browser
         if (hasOwnProperty.call(config, 'check') && !checkedCoverage[browser.id]) {
@@ -250,22 +251,21 @@ var CoverageReporter = function (rootConfig, helper, logger, emitter) {
         }
 
         const context = istanbulLibReport.createContext(options)
-        const tree = istanbulLibReport.summarizers.pkg(remappedCoverageMap)
         const report = reports.create(reporterConfig.type || 'html', options)
 
         // // If reporting to console or in-memory skip directory creation
         const toDisk = !reporterConfig.type || !reporterConfig.type.match(/^(text|text-summary|in-memory)$/)
 
         if (!toDisk && reporterConfig.file === undefined) {
-          tree.visit(report, context)
+          report.execute(context)
           return
         }
 
         helper.mkdirIfNotExists(outputPath, function () {
           log.debug('Writing coverage to %s', outputPath)
-          tree.visit(report, context)
+          report.execute(context)
         })
-      })
+      }))
     }
   }
 
diff --git a/package-lock.json b/package-lock.json
index e826f14..ed0c7db 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -12,12 +12,42 @@
         "@babel/highlight": "^7.8.3"
       }
     },
+    "@babel/core": {
+      "version": "7.9.0",
+      "resolved": "https://registry.npmjs.org/@babel/core/-/core-7.9.0.tgz",
+      "integrity": "sha512-kWc7L0fw1xwvI0zi8OKVBuxRVefwGOrKSQMvrQ3dW+bIIavBY3/NpXmpjMy7bQnLgwgzWQZ8TlM57YHpHNHz4w==",
+      "requires": {
+        "@babel/code-frame": "^7.8.3",
+        "@babel/generator": "^7.9.0",
+        "@babel/helper-module-transforms": "^7.9.0",
+        "@babel/helpers": "^7.9.0",
+        "@babel/parser": "^7.9.0",
+        "@babel/template": "^7.8.6",
+        "@babel/traverse": "^7.9.0",
+        "@babel/types": "^7.9.0",
+        "convert-source-map": "^1.7.0",
+        "debug": "^4.1.0",
+        "gensync": "^1.0.0-beta.1",
+        "json5": "^2.1.2",
+        "lodash": "^4.17.13",
+        "resolve": "^1.3.2",
+        "semver": "^5.4.1",
+        "source-map": "^0.5.0"
+      },
+      "dependencies": {
+        "semver": {
+          "version": "5.7.1",
+          "resolved": "https://registry.npmjs.org/semver/-/semver-5.7.1.tgz",
+          "integrity": "sha512-sauaDf/PZdVgrLTNYHRtpXa1iRiKcaebiKQ1BJdpQlWH2lCvexQdX55snPFyK7QzpudqbCI0qXFfOasHdyNDGQ=="
+        }
+      }
+    },
     "@babel/generator": {
-      "version": "7.8.8",
-      "resolved": "https://registry.npmjs.org/@babel/generator/-/generator-7.8.8.tgz",
-      "integrity": "sha512-HKyUVu69cZoclptr8t8U5b6sx6zoWjh8jiUhnuj3MpZuKT2dJ8zPTuiy31luq32swhI0SpwItCIlU8XW7BZeJg==",
+      "version": "7.9.4",
+      "resolved": "https://registry.npmjs.org/@babel/generator/-/generator-7.9.4.tgz",
+      "integrity": "sha512-rjP8ahaDy/ouhrvCoU1E5mqaitWrxwuNGU+dy1EpaoK48jZay4MdkskKGIMHLZNewg8sAsqpGSREJwP0zH3YQA==",
       "requires": {
-        "@babel/types": "^7.8.7",
+        "@babel/types": "^7.9.0",
         "jsesc": "^2.5.1",
         "lodash": "^4.17.13",
         "source-map": "^0.5.0"
@@ -41,6 +71,64 @@
         "@babel/types": "^7.8.3"
       }
     },
+    "@babel/helper-member-expression-to-functions": {
+      "version": "7.8.3",
+      "resolved": "https://registry.npmjs.org/@babel/helper-member-expression-to-functions/-/helper-member-expression-to-functions-7.8.3.tgz",
+      "integrity": "sha512-fO4Egq88utkQFjbPrSHGmGLFqmrshs11d46WI+WZDESt7Wu7wN2G2Iu+NMMZJFDOVRHAMIkB5SNh30NtwCA7RA==",
+      "requires": {
+        "@babel/types": "^7.8.3"
+      }
+    },
+    "@babel/helper-module-imports": {
+      "version": "7.8.3",
+      "resolved": "https://registry.npmjs.org/@babel/helper-module-imports/-/helper-module-imports-7.8.3.tgz",
+      "integrity": "sha512-R0Bx3jippsbAEtzkpZ/6FIiuzOURPcMjHp+Z6xPe6DtApDJx+w7UYyOLanZqO8+wKR9G10s/FmHXvxaMd9s6Kg==",
+      "requires": {
+        "@babel/types": "^7.8.3"
+      }
+    },
+    "@babel/helper-module-transforms": {
+      "version": "7.9.0",
+      "resolved": "https://registry.npmjs.org/@babel/helper-module-transforms/-/helper-module-transforms-7.9.0.tgz",
+      "integrity": "sha512-0FvKyu0gpPfIQ8EkxlrAydOWROdHpBmiCiRwLkUiBGhCUPRRbVD2/tm3sFr/c/GWFrQ/ffutGUAnx7V0FzT2wA==",
+      "requires": {
+        "@babel/helper-module-imports": "^7.8.3",
+        "@babel/helper-replace-supers": "^7.8.6",
+        "@babel/helper-simple-access": "^7.8.3",
+        "@babel/helper-split-export-declaration": "^7.8.3",
+        "@babel/template": "^7.8.6",
+        "@babel/types": "^7.9.0",
+        "lodash": "^4.17.13"
+      }
+    },
+    "@babel/helper-optimise-call-expression": {
+      "version": "7.8.3",
+      "resolved": "https://registry.npmjs.org/@babel/helper-optimise-call-expression/-/helper-optimise-call-expression-7.8.3.tgz",
+      "integrity": "sha512-Kag20n86cbO2AvHca6EJsvqAd82gc6VMGule4HwebwMlwkpXuVqrNRj6CkCV2sKxgi9MyAUnZVnZ6lJ1/vKhHQ==",
+      "requires": {
+        "@babel/types": "^7.8.3"
+      }
+    },
+    "@babel/helper-replace-supers": {
+      "version": "7.8.6",
+      "resolved": "https://registry.npmjs.org/@babel/helper-replace-supers/-/helper-replace-supers-7.8.6.tgz",
+      "integrity": "sha512-PeMArdA4Sv/Wf4zXwBKPqVj7n9UF/xg6slNRtZW84FM7JpE1CbG8B612FyM4cxrf4fMAMGO0kR7voy1ForHHFA==",
+      "requires": {
+        "@babel/helper-member-expression-to-functions": "^7.8.3",
+        "@babel/helper-optimise-call-expression": "^7.8.3",
+        "@babel/traverse": "^7.8.6",
+        "@babel/types": "^7.8.6"
+      }
+    },
+    "@babel/helper-simple-access": {
+      "version": "7.8.3",
+      "resolved": "https://registry.npmjs.org/@babel/helper-simple-access/-/helper-simple-access-7.8.3.tgz",
+      "integrity": "sha512-VNGUDjx5cCWg4vvCTR8qQ7YJYZ+HBjxOgXEl7ounz+4Sn7+LMD3CFrCTEU6/qXKbA2nKg21CwhhBzO0RpRbdCw==",
+      "requires": {
+        "@babel/template": "^7.8.3",
+        "@babel/types": "^7.8.3"
+      }
+    },
     "@babel/helper-split-export-declaration": {
       "version": "7.8.3",
       "resolved": "https://registry.npmjs.org/@babel/helper-split-export-declaration/-/helper-split-export-declaration-7.8.3.tgz",
@@ -49,6 +137,21 @@
         "@babel/types": "^7.8.3"
       }
     },
+    "@babel/helper-validator-identifier": {
+      "version": "7.9.0",
+      "resolved": "https://registry.npmjs.org/@babel/helper-validator-identifier/-/helper-validator-identifier-7.9.0.tgz",
+      "integrity": "sha512-6G8bQKjOh+of4PV/ThDm/rRqlU7+IGoJuofpagU5GlEl29Vv0RGqqt86ZGRV8ZuSOY3o+8yXl5y782SMcG7SHw=="
+    },
+    "@babel/helpers": {
+      "version": "7.9.2",
+      "resolved": "https://registry.npmjs.org/@babel/helpers/-/helpers-7.9.2.tgz",
+      "integrity": "sha512-JwLvzlXVPjO8eU9c/wF9/zOIN7X6h8DYf7mG4CiFRZRvZNKEF5dQ3H3V+ASkHoIB3mWhatgl5ONhyqHRI6MppA==",
+      "requires": {
+        "@babel/template": "^7.8.3",
+        "@babel/traverse": "^7.9.0",
+        "@babel/types": "^7.9.0"
+      }
+    },
     "@babel/highlight": {
       "version": "7.8.3",
       "resolved": "https://registry.npmjs.org/@babel/highlight/-/highlight-7.8.3.tgz",
@@ -60,9 +163,9 @@
       }
     },
     "@babel/parser": {
-      "version": "7.8.8",
-      "resolved": "https://registry.npmjs.org/@babel/parser/-/parser-7.8.8.tgz",
-      "integrity": "sha512-mO5GWzBPsPf6865iIbzNE0AvkKF3NE+2S3eRUpE+FE07BOAkXh6G+GW/Pj01hhXjve1WScbaIO4UlY1JKeqCcA=="
+      "version": "7.9.4",
+      "resolved": "https://registry.npmjs.org/@babel/parser/-/parser-7.9.4.tgz",
+      "integrity": "sha512-bC49otXX6N0/VYhgOMh4gnP26E9xnDZK3TmbNpxYzzz9BQLBosQwfyOe9/cXUU3txYhTzLCbcqd5c8y/OmCjHA=="
     },
     "@babel/template": {
       "version": "7.8.6",
@@ -75,31 +178,36 @@
       }
     },
     "@babel/traverse": {
-      "version": "7.8.6",
-      "resolved": "https://registry.npmjs.org/@babel/traverse/-/traverse-7.8.6.tgz",
-      "integrity": "sha512-2B8l0db/DPi8iinITKuo7cbPznLCEk0kCxDoB9/N6gGNg/gxOXiR/IcymAFPiBwk5w6TtQ27w4wpElgp9btR9A==",
+      "version": "7.9.0",
+      "resolved": "https://registry.npmjs.org/@babel/traverse/-/traverse-7.9.0.tgz",
+      "integrity": "sha512-jAZQj0+kn4WTHO5dUZkZKhbFrqZE7K5LAQ5JysMnmvGij+wOdr+8lWqPeW0BcF4wFwrEXXtdGO7wcV6YPJcf3w==",
       "requires": {
         "@babel/code-frame": "^7.8.3",
-        "@babel/generator": "^7.8.6",
+        "@babel/generator": "^7.9.0",
         "@babel/helper-function-name": "^7.8.3",
         "@babel/helper-split-export-declaration": "^7.8.3",
-        "@babel/parser": "^7.8.6",
-        "@babel/types": "^7.8.6",
+        "@babel/parser": "^7.9.0",
+        "@babel/types": "^7.9.0",
         "debug": "^4.1.0",
         "globals": "^11.1.0",
         "lodash": "^4.17.13"
       }
     },
     "@babel/types": {
-      "version": "7.8.7",
-      "resolved": "https://registry.npmjs.org/@babel/types/-/types-7.8.7.tgz",
-      "integrity": "sha512-k2TreEHxFA4CjGkL+GYjRyx35W0Mr7DP5+9q6WMkyKXB+904bYmG40syjMFV0oLlhhFCwWl0vA0DyzTDkwAiJw==",
+      "version": "7.9.0",
+      "resolved": "https://registry.npmjs.org/@babel/types/-/types-7.9.0.tgz",
+      "integrity": "sha512-BS9JKfXkzzJl8RluW4JGknzpiUV7ZrvTayM6yfqLTVBEnFtyowVIOu6rqxRd5cVO6yGoWf4T8u8dgK9oB+GCng==",
       "requires": {
-        "esutils": "^2.0.2",
+        "@babel/helper-validator-identifier": "^7.9.0",
         "lodash": "^4.17.13",
         "to-fast-properties": "^2.0.0"
       }
     },
+    "@istanbuljs/schema": {
+      "version": "0.1.2",
+      "resolved": "https://registry.npmjs.org/@istanbuljs/schema/-/schema-0.1.2.tgz",
+      "integrity": "sha512-tsAQNx32a8CoFhjhijUIhI4kccIAgmGhy8LZMZgGfmXcpMbPRUqn5LWmgRttILi6yeGmBJd2xsPkFMs0PzgPCw=="
+    },
     "@sinonjs/commons": {
       "version": "1.7.1",
       "resolved": "https://registry.npmjs.org/@sinonjs/commons/-/commons-1.7.1.tgz",
@@ -865,6 +973,7 @@
       "version": "2.20.3",
       "resolved": "https://registry.npmjs.org/commander/-/commander-2.20.3.tgz",
       "integrity": "sha512-GpVkmM8vF2vQUkj2LvZmD35JxeJOLCwJ9cUkugyk2nuhbv3+mJvpLYYt+0+USMxE+oj+ey/lJEnhZw75x/OMcQ==",
+      "dev": true,
       "optional": true
     },
     "compare-func": {
@@ -1507,6 +1616,14 @@
         }
       }
     },
+    "convert-source-map": {
+      "version": "1.7.0",
+      "resolved": "https://registry.npmjs.org/convert-source-map/-/convert-source-map-1.7.0.tgz",
+      "integrity": "sha512-4FJkXzKXEDB1snCFZlLP4gpC3JILicCpGbzG9f9G7tGqGCzETQ2hWPrcinA9oU4wtf2biUaEH5065UnMeR33oA==",
+      "requires": {
+        "safe-buffer": "~5.1.1"
+      }
+    },
     "cookie": {
       "version": "0.3.1",
       "resolved": "https://registry.npmjs.org/cookie/-/cookie-0.3.1.tgz",
@@ -2718,7 +2835,8 @@
     "fs.realpath": {
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/fs.realpath/-/fs.realpath-1.0.0.tgz",
-      "integrity": "sha1-FQStJSMVjKpA20onh8sBQRmU6k8="
+      "integrity": "sha1-FQStJSMVjKpA20onh8sBQRmU6k8=",
+      "dev": true
     },
     "fsevents": {
       "version": "2.1.2",
@@ -2739,6 +2857,11 @@
       "integrity": "sha1-GwqzvVU7Kg1jmdKcDj6gslIHgyc=",
       "dev": true
     },
+    "gensync": {
+      "version": "1.0.0-beta.1",
+      "resolved": "https://registry.npmjs.org/gensync/-/gensync-1.0.0-beta.1.tgz",
+      "integrity": "sha512-r8EC6NO1sngH/zdD9fiRDLdcgnbayXah+mLgManTaIZJqEC1MZstmnox8KpnI2/fxQwrp5OpCOYWLp4rBl4Jcg=="
+    },
     "get-caller-file": {
       "version": "2.0.5",
       "resolved": "https://registry.npmjs.org/get-caller-file/-/get-caller-file-2.0.5.tgz",
@@ -3107,6 +3230,7 @@
       "version": "7.1.6",
       "resolved": "https://registry.npmjs.org/glob/-/glob-7.1.6.tgz",
       "integrity": "sha512-LwaxwyZ72Lk7vZINtNNrywX0ZuLyStrdDtabefZKAY5ZGJhVtgdznluResxNmPitE0SAO+O26sWTHeKSI2wMBA==",
+      "dev": true,
       "requires": {
         "fs.realpath": "^1.0.0",
         "inflight": "^1.0.4",
@@ -3487,6 +3611,7 @@
       "version": "4.7.3",
       "resolved": "https://registry.npmjs.org/handlebars/-/handlebars-4.7.3.tgz",
       "integrity": "sha512-SRGwSYuNfx8DwHD/6InAPzD6RgeruWLT+B8e8a7gGs8FWgHzlExpTFMEq2IA6QpAfOClpKHy6+8IqTjeBCu6Kg==",
+      "dev": true,
       "requires": {
         "neo-async": "^2.6.0",
         "optimist": "^0.6.1",
@@ -3497,7 +3622,8 @@
         "source-map": {
           "version": "0.6.1",
           "resolved": "https://registry.npmjs.org/source-map/-/source-map-0.6.1.tgz",
-          "integrity": "sha512-UjgapumWlbMhkBgzT7Ykc5YXUT46F0iKu8SGXq0bcwP5dz/h0Plj6enJqjz1Zbq2l5WaqYnrVbwWOWMyF3F47g=="
+          "integrity": "sha512-UjgapumWlbMhkBgzT7Ykc5YXUT46F0iKu8SGXq0bcwP5dz/h0Plj6enJqjz1Zbq2l5WaqYnrVbwWOWMyF3F47g==",
+          "dev": true
         }
       }
     },
@@ -3621,9 +3747,9 @@
       "dev": true
     },
     "html-escaper": {
-      "version": "2.0.0",
-      "resolved": "https://registry.npmjs.org/html-escaper/-/html-escaper-2.0.0.tgz",
-      "integrity": "sha512-a4u9BeERWGu/S8JiWEAQcdrg9v4QArtP9keViQjGMdff20fBdd8waotXaNmODqBe6uZ3Nafi7K/ho4gCQHV3Ig=="
+      "version": "2.0.1",
+      "resolved": "https://registry.npmjs.org/html-escaper/-/html-escaper-2.0.1.tgz",
+      "integrity": "sha512-hNX23TjWwD3q56HpWjUHOKj1+4KKlnjv9PcmBUYKVpga+2cnb9nDx/B1o0yO4n+RZXZdiNxzx6B24C9aNMTkkQ=="
     },
     "http-errors": {
       "version": "1.7.2",
@@ -3767,6 +3893,7 @@
       "version": "1.0.6",
       "resolved": "https://registry.npmjs.org/inflight/-/inflight-1.0.6.tgz",
       "integrity": "sha1-Sb1jMdfQLQwJvJEKEHW6gWW1bfk=",
+      "dev": true,
       "requires": {
         "once": "^1.3.0",
         "wrappy": "1"
@@ -3775,7 +3902,8 @@
     "inherits": {
       "version": "2.0.4",
       "resolved": "https://registry.npmjs.org/inherits/-/inherits-2.0.4.tgz",
-      "integrity": "sha512-k/vGaX4/Yla3WzyMCvTQOXYeIHvqOKtnqBduzTHpzpQZzAskKMhZ2K+EnBiSM9zGSoIFeMpXKxa4dYeZIQqewQ=="
+      "integrity": "sha512-k/vGaX4/Yla3WzyMCvTQOXYeIHvqOKtnqBduzTHpzpQZzAskKMhZ2K+EnBiSM9zGSoIFeMpXKxa4dYeZIQqewQ==",
+      "dev": true
     },
     "ini": {
       "version": "1.3.5",
@@ -4203,6 +4331,17 @@
           "requires": {
             "glob": "5.x",
             "minimatch": "2.x"
+          },
+          "dependencies": {
+            "minimatch": {
+              "version": "2.0.10",
+              "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-2.0.10.tgz",
+              "integrity": "sha1-jQh8OcazjAAbl/ynzm0OHoCvusc=",
+              "dev": true,
+              "requires": {
+                "brace-expansion": "^1.0.0"
+              }
+            }
           }
         },
         "glob": {
@@ -4225,12 +4364,12 @@
           "dev": true
         },
         "minimatch": {
-          "version": "2.0.10",
-          "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-2.0.10.tgz",
-          "integrity": "sha1-jQh8OcazjAAbl/ynzm0OHoCvusc=",
+          "version": "3.0.4",
+          "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-3.0.4.tgz",
+          "integrity": "sha512-yJHVQEhyqPLUTgt9B83PXu6W3rx4MvvHvSUvToogpwoGDOUQ+yDrR0HRot+yOCdCO7u4hX3pWft6kWBBcqh0UA==",
           "dev": true,
           "requires": {
-            "brace-expansion": "^1.0.0"
+            "brace-expansion": "^1.1.7"
           }
         },
         "resolve": {
@@ -4257,53 +4396,56 @@
       }
     },
     "istanbul-lib-coverage": {
-      "version": "2.0.5",
-      "resolved": "https://registry.npmjs.org/istanbul-lib-coverage/-/istanbul-lib-coverage-2.0.5.tgz",
-      "integrity": "sha512-8aXznuEPCJvGnMSRft4udDRDtb1V3pkQkMMI5LI+6HuQz5oQ4J2UFn1H82raA3qJtyOLkkwVqICBQkjnGtn5mA=="
+      "version": "3.0.0",
+      "resolved": "https://registry.npmjs.org/istanbul-lib-coverage/-/istanbul-lib-coverage-3.0.0.tgz",
+      "integrity": "sha512-UiUIqxMgRDET6eR+o5HbfRYP1l0hqkWOs7vNxC/mggutCMUIhWMm8gAHb8tHlyfD3/l6rlgNA5cKdDzEAf6hEg=="
     },
     "istanbul-lib-instrument": {
-      "version": "3.3.0",
-      "resolved": "https://registry.npmjs.org/istanbul-lib-instrument/-/istanbul-lib-instrument-3.3.0.tgz",
-      "integrity": "sha512-5nnIN4vo5xQZHdXno/YDXJ0G+I3dAm4XgzfSVTPLQpj/zAV2dV6Juy0yaf10/zrJOJeHoN3fraFe+XRq2bFVZA==",
-      "requires": {
-        "@babel/generator": "^7.4.0",
-        "@babel/parser": "^7.4.3",
-        "@babel/template": "^7.4.0",
-        "@babel/traverse": "^7.4.3",
-        "@babel/types": "^7.4.0",
-        "istanbul-lib-coverage": "^2.0.5",
-        "semver": "^6.0.0"
+      "version": "4.0.1",
+      "resolved": "https://registry.npmjs.org/istanbul-lib-instrument/-/istanbul-lib-instrument-4.0.1.tgz",
+      "integrity": "sha512-imIchxnodll7pvQBYOqUu88EufLCU56LMeFPZZM/fJZ1irYcYdqroaV+ACK1Ila8ls09iEYArp+nqyC6lW1Vfg==",
+      "requires": {
+        "@babel/core": "^7.7.5",
+        "@babel/parser": "^7.7.5",
+        "@babel/template": "^7.7.4",
+        "@babel/traverse": "^7.7.4",
+        "@istanbuljs/schema": "^0.1.2",
+        "istanbul-lib-coverage": "^3.0.0",
+        "semver": "^6.3.0"
       }
     },
     "istanbul-lib-report": {
-      "version": "2.0.8",
-      "resolved": "https://registry.npmjs.org/istanbul-lib-report/-/istanbul-lib-report-2.0.8.tgz",
-      "integrity": "sha512-fHBeG573EIihhAblwgxrSenp0Dby6tJMFR/HvlerBsrCTD5bkUuoNtn3gVh29ZCS824cGGBPn7Sg7cNk+2xUsQ==",
+      "version": "3.0.0",
+      "resolved": "https://registry.npmjs.org/istanbul-lib-report/-/istanbul-lib-report-3.0.0.tgz",
+      "integrity": "sha512-wcdi+uAKzfiGT2abPpKZ0hSU1rGQjUQnLvtY5MpQ7QCTahD3VODhcu4wcfY1YtkGaDD5yuydOLINXsfbus9ROw==",
       "requires": {
-        "istanbul-lib-coverage": "^2.0.5",
-        "make-dir": "^2.1.0",
-        "supports-color": "^6.1.0"
+        "istanbul-lib-coverage": "^3.0.0",
+        "make-dir": "^3.0.0",
+        "supports-color": "^7.1.0"
       },
       "dependencies": {
+        "has-flag": {
+          "version": "4.0.0",
+          "resolved": "https://registry.npmjs.org/has-flag/-/has-flag-4.0.0.tgz",
+          "integrity": "sha512-EykJT/Q1KjTWctppgIAgfSO0tKVuZUjhgMr17kqTumMl6Afv3EISleU7qZUzoXDFTAHTDC4NOoG/ZxU3EvlMPQ=="
+        },
         "supports-color": {
-          "version": "6.1.0",
-          "resolved": "https://registry.npmjs.org/supports-color/-/supports-color-6.1.0.tgz",
-          "integrity": "sha512-qe1jfm1Mg7Nq/NSh6XE24gPXROEVsWHxC1LIx//XNlD9iw7YZQGjZNjYN7xGaEG6iKdA8EtNFW6R0gjnVXp+wQ==",
+          "version": "7.1.0",
+          "resolved": "https://registry.npmjs.org/supports-color/-/supports-color-7.1.0.tgz",
+          "integrity": "sha512-oRSIpR8pxT1Wr2FquTNnGet79b3BWljqOuoW/h4oBhxJ/HUbX5nX6JSruTkvXDCFMwDPvsaTTbvMLKZWSy0R5g==",
           "requires": {
-            "has-flag": "^3.0.0"
+            "has-flag": "^4.0.0"
           }
         }
       }
     },
     "istanbul-lib-source-maps": {
-      "version": "3.0.6",
-      "resolved": "https://registry.npmjs.org/istanbul-lib-source-maps/-/istanbul-lib-source-maps-3.0.6.tgz",
-      "integrity": "sha512-R47KzMtDJH6X4/YW9XTx+jrLnZnscW4VpNN+1PViSYTejLVPWv7oov+Duf8YQSPyVRUvueQqz1TcsC6mooZTXw==",
+      "version": "4.0.0",
+      "resolved": "https://registry.npmjs.org/istanbul-lib-source-maps/-/istanbul-lib-source-maps-4.0.0.tgz",
+      "integrity": "sha512-c16LpFRkR8vQXyHZ5nLpY35JZtzj1PQY1iZmesUbf1FZHbIupcWfjgOXBY9YHkLEQ6puz1u4Dgj6qmU/DisrZg==",
       "requires": {
         "debug": "^4.1.1",
-        "istanbul-lib-coverage": "^2.0.5",
-        "make-dir": "^2.1.0",
-        "rimraf": "^2.6.3",
+        "istanbul-lib-coverage": "^3.0.0",
         "source-map": "^0.6.1"
       },
       "dependencies": {
@@ -4315,11 +4457,12 @@
       }
     },
     "istanbul-reports": {
-      "version": "2.2.7",
-      "resolved": "https://registry.npmjs.org/istanbul-reports/-/istanbul-reports-2.2.7.tgz",
-      "integrity": "sha512-uu1F/L1o5Y6LzPVSVZXNOoD/KXpJue9aeLRd0sM9uMXfZvzomB0WxVamWb5ue8kA2vVWEmW7EG+A5n3f1kqHKg==",
+      "version": "3.0.0",
+      "resolved": "https://registry.npmjs.org/istanbul-reports/-/istanbul-reports-3.0.0.tgz",
+      "integrity": "sha512-2osTcC8zcOSUkImzN2EWQta3Vdi4WjjKw99P2yWx5mLnigAM0Rd5uYFn1cf2i/Ois45GkNjaoTqc5CxgMSX80A==",
       "requires": {
-        "html-escaper": "^2.0.0"
+        "html-escaper": "^2.0.0",
+        "istanbul-lib-report": "^3.0.0"
       }
     },
     "js-tokens": {
@@ -4366,6 +4509,14 @@
       "integrity": "sha1-Epai1Y/UXxmg9s4B1lcB4sc1tus=",
       "dev": true
     },
+    "json5": {
+      "version": "2.1.2",
+      "resolved": "https://registry.npmjs.org/json5/-/json5-2.1.2.tgz",
+      "integrity": "sha512-MoUOQ4WdiN3yxhm7NEVJSJrieAo5hNSLQ5sj05OTRHPL9HOBy8u4Bu88jsC1jvqAdN+E1bJmsUcZH+1HQxliqQ==",
+      "requires": {
+        "minimist": "^1.2.5"
+      }
+    },
     "jsonfile": {
       "version": "4.0.0",
       "resolved": "https://registry.npmjs.org/jsonfile/-/jsonfile-4.0.0.tgz",
@@ -4704,19 +4855,11 @@
       "dev": true
     },
     "make-dir": {
-      "version": "2.1.0",
-      "resolved": "https://registry.npmjs.org/make-dir/-/make-dir-2.1.0.tgz",
-      "integrity": "sha512-LS9X+dc8KLxXCb8dni79fLIIUA5VyZoyjSMCwTluaXA0o27cCK0bhXkpgw+sTXVpPy/lSO57ilRixqk0vDmtRA==",
+      "version": "3.0.2",
+      "resolved": "https://registry.npmjs.org/make-dir/-/make-dir-3.0.2.tgz",
+      "integrity": "sha512-rYKABKutXa6vXTXhoV18cBE7PaewPXHe/Bdq4v+ZLMhxbWApkFFplT0LcbMW+6BbjnQXzZ/sAvSE/JdguApG5w==",
       "requires": {
-        "pify": "^4.0.1",
-        "semver": "^5.6.0"
-      },
-      "dependencies": {
-        "semver": {
-          "version": "5.7.1",
-          "resolved": "https://registry.npmjs.org/semver/-/semver-5.7.1.tgz",
-          "integrity": "sha512-sauaDf/PZdVgrLTNYHRtpXa1iRiKcaebiKQ1BJdpQlWH2lCvexQdX55snPFyK7QzpudqbCI0qXFfOasHdyNDGQ=="
-        }
+        "semver": "^6.0.0"
       }
     },
     "make-iterator": {
@@ -4913,8 +5056,7 @@
     "minimist": {
       "version": "1.2.5",
       "resolved": "https://registry.npmjs.org/minimist/-/minimist-1.2.5.tgz",
-      "integrity": "sha512-FM9nNUYrRBAELZQT3xeZQ7fmMOBg6nWNmJKTcgsJeaLstP/UODVpGsr5OhXhhXg6f+qtJ8uiZ+PUxkDWcgIXLw==",
-      "dev": true
+      "integrity": "sha512-FM9nNUYrRBAELZQT3xeZQ7fmMOBg6nWNmJKTcgsJeaLstP/UODVpGsr5OhXhhXg6f+qtJ8uiZ+PUxkDWcgIXLw=="
     },
     "minimist-options": {
       "version": "3.0.2",
@@ -5403,6 +5545,7 @@
       "version": "1.4.0",
       "resolved": "https://registry.npmjs.org/once/-/once-1.4.0.tgz",
       "integrity": "sha1-WDsap3WWHUsROsF9nFC6753Xa9E=",
+      "dev": true,
       "requires": {
         "wrappy": "1"
       }
@@ -5574,7 +5717,8 @@
     "path-is-absolute": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/path-is-absolute/-/path-is-absolute-1.0.1.tgz",
-      "integrity": "sha1-F0uSaHNVNP+8es5r9TpanhtcX18="
+      "integrity": "sha1-F0uSaHNVNP+8es5r9TpanhtcX18=",
+      "dev": true
     },
     "path-key": {
       "version": "2.0.1",
@@ -5585,8 +5729,7 @@
     "path-parse": {
       "version": "1.0.6",
       "resolved": "https://registry.npmjs.org/path-parse/-/path-parse-1.0.6.tgz",
-      "integrity": "sha512-GSmOT2EbHrINBf9SR7CDELwlJ8AENk3Qn7OikK4nFYAu3Ote2+JYNVvkpAEQm3/TLNEJFD/xZJjzyxg3KBWOzw==",
-      "dev": true
+      "integrity": "sha512-GSmOT2EbHrINBf9SR7CDELwlJ8AENk3Qn7OikK4nFYAu3Ote2+JYNVvkpAEQm3/TLNEJFD/xZJjzyxg3KBWOzw=="
     },
     "path-root": {
       "version": "0.1.1",
@@ -5649,11 +5792,6 @@
       "integrity": "sha512-ISBaA8xQNmwELC7eOjqFKMESB2VIqt4PPDD0nsS95b/9dZXvVKOlz9keMSnoGGKcOHXfTvDD6WMaRoSc9UuhRA==",
       "dev": true
     },
-    "pify": {
-      "version": "4.0.1",
-      "resolved": "https://registry.npmjs.org/pify/-/pify-4.0.1.tgz",
-      "integrity": "sha512-uB80kBFb/tfd68bVleG9T5GGsGPjJrLAUpR5PZIrhBnIaRTQRjqdJSsIKkOP6OAIFbj7GOrcudc5pNjZ+geV2g=="
-    },
     "pinkie": {
       "version": "2.0.4",
       "resolved": "https://registry.npmjs.org/pinkie/-/pinkie-2.0.4.tgz",
@@ -5948,7 +6086,6 @@
       "version": "1.15.1",
       "resolved": "https://registry.npmjs.org/resolve/-/resolve-1.15.1.tgz",
       "integrity": "sha512-84oo6ZTtoTUpjgNEr5SJyzQhzL72gaRodsSfyxC/AXRvwu0Yse9H8eF9IpGo7b8YetZhlI6v7ZQ6bKBFV/6S7w==",
-      "dev": true,
       "requires": {
         "path-parse": "^1.0.6"
       }
@@ -6018,6 +6155,7 @@
       "version": "2.7.1",
       "resolved": "https://registry.npmjs.org/rimraf/-/rimraf-2.7.1.tgz",
       "integrity": "sha512-uWjbaKIK3T1OSVptzX7Nl6PvQ3qAGtKEtVRjRuazjfL3Bx5eI409VZSqgND+4UNnmzLVdPj9FqFJNPqBZFve4w==",
+      "dev": true,
       "requires": {
         "glob": "^7.1.3"
       }
@@ -6043,8 +6181,7 @@
     "safe-buffer": {
       "version": "5.1.2",
       "resolved": "https://registry.npmjs.org/safe-buffer/-/safe-buffer-5.1.2.tgz",
-      "integrity": "sha512-Gd2UZBJDkXlY7GbJxfsE8/nvKkUEU1G38c1siN6QP6a9PT9MmHB8GnpscSmMJSoF8LOIrt8ud/wPtojys4G6+g==",
-      "dev": true
+      "integrity": "sha512-Gd2UZBJDkXlY7GbJxfsE8/nvKkUEU1G38c1siN6QP6a9PT9MmHB8GnpscSmMJSoF8LOIrt8ud/wPtojys4G6+g=="
     },
     "safe-regex": {
       "version": "1.1.0",
@@ -6856,6 +6993,7 @@
       "version": "3.8.0",
       "resolved": "https://registry.npmjs.org/uglify-js/-/uglify-js-3.8.0.tgz",
       "integrity": "sha512-ugNSTT8ierCsDHso2jkBHXYrU8Y5/fY2ZUprfrJUiD7YpuFvV4jODLFmb3h4btQjqr5Nh4TX4XtgDfCU1WdioQ==",
+      "dev": true,
       "optional": true,
       "requires": {
         "commander": "~2.20.3",
@@ -6866,6 +7004,7 @@
           "version": "0.6.1",
           "resolved": "https://registry.npmjs.org/source-map/-/source-map-0.6.1.tgz",
           "integrity": "sha512-UjgapumWlbMhkBgzT7Ykc5YXUT46F0iKu8SGXq0bcwP5dz/h0Plj6enJqjz1Zbq2l5WaqYnrVbwWOWMyF3F47g==",
+          "dev": true,
           "optional": true
         }
       }
@@ -7150,7 +7289,8 @@
     "wrappy": {
       "version": "1.0.2",
       "resolved": "https://registry.npmjs.org/wrappy/-/wrappy-1.0.2.tgz",
-      "integrity": "sha1-tSQ9jz7BqjXxNkYFvA0QNuMKtp8="
+      "integrity": "sha1-tSQ9jz7BqjXxNkYFvA0QNuMKtp8=",
+      "dev": true
     },
     "write": {
       "version": "1.0.3",
diff --git a/package.json b/package.json
index d8d8be5..b591401 100644
--- a/package.json
+++ b/package.json
@@ -19,12 +19,12 @@
   ],
   "author": "SATO taichi <ryushi@gmail.com>",
   "dependencies": {
-    "istanbul-lib-coverage": "^2.0.5",
-    "istanbul-lib-instrument": "^3.3.0",
-    "istanbul-lib-report": "^2.0.8",
-    "istanbul-lib-source-maps": "^3.0.6",
-    "istanbul-reports": "^2.2.4",
-    "minimatch": "^3.0.0"
+    "istanbul-lib-coverage": "^3.0.0",
+    "istanbul-lib-instrument": "^4.0.1",
+    "istanbul-lib-report": "^3.0.0",
+    "istanbul-lib-source-maps": "^4.0.0",
+    "istanbul-reports": "^3.0.0",
+    "minimatch": "^3.0.4"
   },
   "license": "MIT",
   "devDependencies": {
diff --git a/test/reporter.spec.js b/test/reporter.spec.js
index 31c6f62..de95615 100644
--- a/test/reporter.spec.js
+++ b/test/reporter.spec.js
@@ -44,7 +44,6 @@ describe('reporter', () => {
   let createCoverageSummaryStub = null
   let createCoverageMapStub = null
   let createContextStub = null
-  let packageSummaryStub = null
   let getDefaultWatermarkStub = null
   let sourceMapStoreGetStub = null
   let globalCoverageMapGetStub = null
@@ -82,19 +81,14 @@ describe('reporter', () => {
       functions: [50, 80],
       lines: [50, 80]
     }
-    mockPackageSummary = {
-      visit: sinon.stub()
-    }
     createContextStub = sinon.stub(istanbulLibReport, 'createContext')
-    packageSummaryStub = sinon.stub(istanbulLibReport.summarizers, 'pkg')
-    packageSummaryStub.returns(mockPackageSummary)
     getDefaultWatermarkStub = sinon.stub(istanbulLibReport, 'getDefaultWatermarks')
     getDefaultWatermarkStub.returns(mockDefaultWatermarks)
 
     mockSourceMapStore = {
       transformCoverage: sinon.stub()
     }
-    mockSourceMapStore.transformCoverage.returns({ map: mockCoverageMap })
+    mockSourceMapStore.transformCoverage.resolves(mockCoverageMap)
     sourceMapStoreGetStub = sinon.stub(globalSourceMapStore, 'get')
     sourceMapStoreGetStub.returns(mockSourceMapStore)
 
@@ -103,7 +97,9 @@ describe('reporter', () => {
     globalCoverageMapGetStub.returns(mockGlobalCoverageMap)
     sinon.stub(globalCoverageMap, 'add')
 
+    mockPackageSummary = { execute: sinon.stub() }
     reportCreateStub = sinon.stub(reports, 'create')
+    reportCreateStub.returns(mockPackageSummary)
 
     m = loadFile(path.join(__dirname, '/../lib/reporter.js'), mocks)
   })
@@ -162,22 +158,22 @@ describe('reporter', () => {
       expect(mockCoverageMap.merge).not.to.have.been.called
     })
 
-    it('should make reports', () => {
-      reporter.onRunComplete(browsers)
+    it('should make reports', async () => {
+      await reporter.onRunComplete(browsers)
       expect(mkdirIfNotExistsStub).to.have.been.calledTwice
       const dir = rootConfig.coverageReporter.dir
       expect(mkdirIfNotExistsStub.getCall(0).args[0]).to.deep.equal(resolve('/base', dir, fakeChrome.name))
       expect(mkdirIfNotExistsStub.getCall(1).args[0]).to.deep.equal(resolve('/base', dir, fakeOpera.name))
       mkdirIfNotExistsStub.getCall(0).args[1]()
       expect(reportCreateStub).to.have.been.called
-      expect(mockPackageSummary.visit).to.have.been.called
+      expect(mockPackageSummary.execute).to.have.been.called
       const createArgs = reportCreateStub.getCall(0).args
       expect(createArgs[0]).to.be.equal('html')
       expect(createArgs[1].browser).to.be.equal(fakeChrome)
       expect(createArgs[1].emitter).to.be.equal(emitter)
     })
 
-    it('should support a string for the subdir option', () => {
+    it('should support a string for the subdir option', async () => {
       const customConfig = helper.merge({}, rootConfig, {
         coverageReporter: {
           subdir: 'test'
@@ -188,7 +184,7 @@ describe('reporter', () => {
       reporter.onRunStart()
       browsers.forEach(b => reporter.onBrowserStart(b))
 
-      reporter.onRunComplete(browsers)
+      await reporter.onRunComplete(browsers)
       expect(mkdirIfNotExistsStub).to.have.been.calledTwice
       const dir = customConfig.coverageReporter.dir
       const subdir = customConfig.coverageReporter.subdir
@@ -196,10 +192,10 @@ describe('reporter', () => {
       expect(mkdirIfNotExistsStub.getCall(1).args[0]).to.deep.equal(resolve('/base', dir, subdir))
       mkdirIfNotExistsStub.getCall(0).args[1]()
       expect(reportCreateStub).to.have.been.called
-      expect(mockPackageSummary.visit).to.have.been.called
+      expect(mockPackageSummary.execute).to.have.been.called
     })
 
-    it('should support a function for the subdir option', () => {
+    it('should support a function for the subdir option', async () => {
       const customConfig = helper.merge({}, rootConfig, {
         coverageReporter: {
           subdir: (browserName) => browserName.toLowerCase().split(/[ /-]/)[0]
@@ -210,17 +206,17 @@ describe('reporter', () => {
       reporter.onRunStart()
       browsers.forEach(b => reporter.onBrowserStart(b))
 
-      reporter.onRunComplete(browsers)
+      await reporter.onRunComplete(browsers)
       expect(mkdirIfNotExistsStub).to.have.been.calledTwice
       const dir = customConfig.coverageReporter.dir
       expect(mkdirIfNotExistsStub.getCall(0).args[0]).to.deep.equal(resolve('/base', dir, 'chrome'))
       expect(mkdirIfNotExistsStub.getCall(1).args[0]).to.deep.equal(resolve('/base', dir, 'opera'))
       mkdirIfNotExistsStub.getCall(0).args[1]()
       expect(reportCreateStub).to.have.been.called
-      expect(mockPackageSummary.visit).to.have.been.called
+      expect(mockPackageSummary.execute).to.have.been.called
     })
 
-    it('should support a specific dir and subdir per reporter', () => {
+    it('should support a specific dir and subdir per reporter', async () => {
       const customConfig = helper.merge({}, rootConfig, {
         coverageReporter: {
           dir: 'useless',
@@ -242,7 +238,7 @@ describe('reporter', () => {
       reporter.onRunStart()
       browsers.forEach(b => reporter.onBrowserStart(b))
 
-      reporter.onRunComplete(browsers)
+      await reporter.onRunComplete(browsers)
       expect(mkdirIfNotExistsStub.callCount).to.equal(4)
       expect(mkdirIfNotExistsStub.getCall(0).args[0]).to.deep.equal(resolve('/base', 'reporter1', 'chrome'))
       expect(mkdirIfNotExistsStub.getCall(1).args[0]).to.deep.equal(resolve('/base', 'reporter1', 'opera'))
@@ -250,10 +246,10 @@ describe('reporter', () => {
       expect(mkdirIfNotExistsStub.getCall(3).args[0]).to.deep.equal(resolve('/base', 'reporter2', 'OPERA'))
       mkdirIfNotExistsStub.getCall(0).args[1]()
       expect(reportCreateStub).to.have.been.called
-      expect(mockPackageSummary.visit).to.have.been.called
+      expect(mockPackageSummary.execute).to.have.been.called
     })
 
-    it('should fallback to the default dir/subdir if not provided', () => {
+    it('should fallback to the default dir/subdir if not provided', async () => {
       const customConfig = helper.merge({}, rootConfig, {
         coverageReporter: {
           dir: 'defaultdir',
@@ -273,7 +269,7 @@ describe('reporter', () => {
       reporter.onRunStart()
       browsers.forEach(b => reporter.onBrowserStart(b))
 
-      reporter.onRunComplete(browsers)
+      await reporter.onRunComplete(browsers)
       expect(mkdirIfNotExistsStub.callCount).to.equal(4)
       expect(mkdirIfNotExistsStub.getCall(0).args[0]).to.deep.equal(resolve('/base', 'reporter1', 'defaultsubdir'))
       expect(mkdirIfNotExistsStub.getCall(1).args[0]).to.deep.equal(resolve('/base', 'reporter1', 'defaultsubdir'))
@@ -281,40 +277,40 @@ describe('reporter', () => {
       expect(mkdirIfNotExistsStub.getCall(3).args[0]).to.deep.equal(resolve('/base', 'defaultdir', 'OPERA'))
       mkdirIfNotExistsStub.getCall(0).args[1]()
       expect(reportCreateStub).to.have.been.called
-      expect(mockPackageSummary.visit).to.have.been.called
+      expect(mockPackageSummary.execute).to.have.been.called
     })
 
-    it('should not create directory if reporting text* to console', () => {
+    it('should not create directory if reporting text* to console', async () => {
       const run = () => {
         reporter = new m.CoverageReporter(rootConfig, mockHelper, mockLogger)
         reporter.onRunStart()
         browsers.forEach(b => reporter.onBrowserStart(b))
-        reporter.onRunComplete(browsers)
+        return reporter.onRunComplete(browsers)
       }
 
       rootConfig.coverageReporter.reporters = [
         { type: 'text' },
         { type: 'text-summary' }
       ]
-      run()
+      await run()
       expect(mkdirIfNotExistsStub).not.to.have.been.called
     })
 
-    it('should create directory if reporting text* to file', () => {
+    it('should create directory if reporting text* to file', async () => {
       const run = () => {
         reporter = new m.CoverageReporter(rootConfig, mockHelper, mockLogger)
         reporter.onRunStart()
         browsers.forEach(b => reporter.onBrowserStart(b))
-        reporter.onRunComplete(browsers)
+        return reporter.onRunComplete(browsers)
       }
 
       rootConfig.coverageReporter.reporters = [{ type: 'text', file: 'file' }]
-      run()
+      await run()
       expect(mkdirIfNotExistsStub).to.have.been.calledTwice
 
       mkdirIfNotExistsStub.resetHistory()
       rootConfig.coverageReporter.reporters = [{ type: 'text-summary', file: 'file' }]
-      run()
+      await run()
       expect(mkdirIfNotExistsStub).to.have.been.calledTwice
     })
 
@@ -370,7 +366,7 @@ describe('reporter', () => {
       expect(globalCoverageMapGetStub).not.to.have.been.called
     })
 
-    it('should pass watermarks to istanbul', () => {
+    it('should pass watermarks to istanbul', async () => {
       const watermarks = {
         statements: [10, 20],
         branches: [30, 40],
@@ -395,7 +391,7 @@ describe('reporter', () => {
       reporter = new m.CoverageReporter(customConfig, mockHelper, mockLogger)
       reporter.onRunStart()
       browsers.forEach(b => reporter.onBrowserStart(b))
-      reporter.onRunComplete(browsers)
+      await reporter.onRunComplete(browsers)
 
       expect(createContextStub).to.have.been.called
       expect(reportCreateStub).to.have.been.called
@@ -403,7 +399,7 @@ describe('reporter', () => {
       expect(options.args[1].watermarks).to.deep.equal(watermarks)
     })
 
-    it('should merge with istanbul default watermarks', () => {
+    it('should merge with istanbul default watermarks', async () => {
       const watermarks = {
         statements: [10, 20],
         lines: [70, 80]
@@ -426,7 +422,7 @@ describe('reporter', () => {
       reporter = new m.CoverageReporter(customConfig, mockHelper, mockLogger)
       reporter.onRunStart()
       browsers.forEach(b => reporter.onBrowserStart(b))
-      reporter.onRunComplete(browsers)
+      await reporter.onRunComplete(browsers)
 
       expect(createContextStub).to.have.been.called
       expect(reportCreateStub).to.have.been.called
@@ -437,7 +433,7 @@ describe('reporter', () => {
       expect(options.args[1].watermarks.lines).to.deep.equal(watermarks.lines)
     })
 
-    it('should log errors on low coverage and fail the build', () => {
+    it('should log errors on low coverage and fail the build', async () => {
       const customConfig = helper.merge({}, rootConfig, {
         coverageReporter: {
           check: {
@@ -472,13 +468,13 @@ describe('reporter', () => {
       reporter = new m.CoverageReporter(customConfig, mockHelper, customLogger)
       reporter.onRunStart()
       browsers.forEach(b => reporter.onBrowserStart(b))
-      reporter.onRunComplete(browsers, results)
+      await reporter.onRunComplete(browsers, results)
 
       expect(spy1).to.have.been.called
       expect(results.exitCode).to.not.equal(0)
     })
 
-    it('should not log errors on sufficient coverage and not fail the build', () => {
+    it('should not log errors on sufficient coverage and not fail the build', async () => {
       const customConfig = helper.merge({}, rootConfig, {
         coverageReporter: {
           check: {
@@ -513,7 +509,7 @@ describe('reporter', () => {
       reporter = new m.CoverageReporter(customConfig, mockHelper, customLogger)
       reporter.onRunStart()
       browsers.forEach(b => reporter.onBrowserStart(b))
-      reporter.onRunComplete(browsers, results)
+      await reporter.onRunComplete(browsers, results)
 
       expect(spy1).to.not.have.been.called