diff --git a/src/__tests__/fixtures/asset-tag/__snapshots__/webpack4/server--main.js b/src/__tests__/fixtures/asset-tag/__snapshots__/webpack4/server--main.js
index 96c99d8..96e99b1 100644
--- a/src/__tests__/fixtures/asset-tag/__snapshots__/webpack4/server--main.js
+++ b/src/__tests__/fixtures/asset-tag/__snapshots__/webpack4/server--main.js
@@ -199,12 +199,41 @@ function outEndOverride(data, encoding, callback) {
 const _marko_componentType = "wUwFs+xe",
       _marko_component = {};
 _marko_template._ = marko_dist_runtime_components_renderer__WEBPACK_IMPORTED_MODULE_5___default()(function (input, out, _component, component, state) {
-  out.___flush = out.flush;
-  out.___end = out.end;
-  out.___renderAssets = renderAssets;
-  out.___assets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_1__["default"].getAssets("test_wUwF", out.global.buildName);
-  out.flush = outFlushOverride;
-  out.end = outEndOverride;
+  const curAssets = out.___assets;
+  const newAssets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_1__["default"].getAssets("test_wUwF", out.global.buildName);
+
+  if (curAssets) {
+    if (newAssets.js) {
+      if (curAssets.js) {
+        for (const js of newAssets.js) {
+          if (!curAssets.js.includes(js)) {
+            curAssets.js.push(js);
+          }
+        }
+      } else {
+        curAssets.js = newAssets.js;
+      }
+    }
+
+    if (newAssets.css) {
+      if (curAssets.css) {
+        for (const css of newAssets.css) {
+          if (!curAssets.css.includes(css)) {
+            curAssets.css.push(css);
+          }
+        }
+      } else {
+        curAssets.css = newAssets.css;
+      }
+    }
+  } else {
+    out.___flush = out.flush;
+    out.___end = out.end;
+    out.___renderAssets = renderAssets;
+    out.___assets = newAssets;
+    out.flush = outFlushOverride;
+    out.end = outEndOverride;
+  }
 
   marko_dist_runtime_helpers_render_tag__WEBPACK_IMPORTED_MODULE_2___default()(_test_marko__WEBPACK_IMPORTED_MODULE_0__["default"], input, out, _component, "0");
 
diff --git a/src/__tests__/fixtures/asset-tag/__snapshots__/webpack5/server--main.js b/src/__tests__/fixtures/asset-tag/__snapshots__/webpack5/server--main.js
index 9db24f1..5dd6fc7 100644
--- a/src/__tests__/fixtures/asset-tag/__snapshots__/webpack5/server--main.js
+++ b/src/__tests__/fixtures/asset-tag/__snapshots__/webpack5/server--main.js
@@ -187,12 +187,41 @@ function outEndOverride(data, encoding, callback) {
 const _marko_componentType = "wUwFs+xe",
       _marko_component = {};
 _marko_template._ = marko_dist_runtime_components_renderer__WEBPACK_IMPORTED_MODULE_6___default()(function (input, out, _component, component, state) {
-  out.___flush = out.flush;
-  out.___end = out.end;
-  out.___renderAssets = renderAssets;
-  out.___assets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_2__.default.getAssets("test_wUwF", out.global.buildName);
-  out.flush = outFlushOverride;
-  out.end = outEndOverride;
+  const curAssets = out.___assets;
+  const newAssets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_2__.default.getAssets("test_wUwF", out.global.buildName);
+
+  if (curAssets) {
+    if (newAssets.js) {
+      if (curAssets.js) {
+        for (const js of newAssets.js) {
+          if (!curAssets.js.includes(js)) {
+            curAssets.js.push(js);
+          }
+        }
+      } else {
+        curAssets.js = newAssets.js;
+      }
+    }
+
+    if (newAssets.css) {
+      if (curAssets.css) {
+        for (const css of newAssets.css) {
+          if (!curAssets.css.includes(css)) {
+            curAssets.css.push(css);
+          }
+        }
+      } else {
+        curAssets.css = newAssets.css;
+      }
+    }
+  } else {
+    out.___flush = out.flush;
+    out.___end = out.end;
+    out.___renderAssets = renderAssets;
+    out.___assets = newAssets;
+    out.flush = outFlushOverride;
+    out.end = outEndOverride;
+  }
 
   marko_dist_runtime_helpers_render_tag__WEBPACK_IMPORTED_MODULE_3___default()(_test_marko__WEBPACK_IMPORTED_MODULE_1__.default, input, out, _component, "0");
 
diff --git a/src/__tests__/fixtures/basic-template-plugin-custom-runtime-id/__snapshots__/webpack4/server--main.js b/src/__tests__/fixtures/basic-template-plugin-custom-runtime-id/__snapshots__/webpack4/server--main.js
index e708d99..ffb5faf 100644
--- a/src/__tests__/fixtures/basic-template-plugin-custom-runtime-id/__snapshots__/webpack4/server--main.js
+++ b/src/__tests__/fixtures/basic-template-plugin-custom-runtime-id/__snapshots__/webpack4/server--main.js
@@ -122,12 +122,41 @@ const _marko_componentType = "8XgZ/c27",
       _marko_component = {};
 _marko_template._ = marko_dist_runtime_components_renderer__WEBPACK_IMPORTED_MODULE_5___default()(function (input, out, _component, component, state) {
   out.global.runtimeId = "testruntime";
-  out.___flush = out.flush;
-  out.___end = out.end;
-  out.___renderAssets = renderAssets;
-  out.___assets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_1__["default"].getAssets("test_8XgZ", out.global.buildName);
-  out.flush = outFlushOverride;
-  out.end = outEndOverride;
+  const curAssets = out.___assets;
+  const newAssets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_1__["default"].getAssets("test_8XgZ", out.global.buildName);
+
+  if (curAssets) {
+    if (newAssets.js) {
+      if (curAssets.js) {
+        for (const js of newAssets.js) {
+          if (!curAssets.js.includes(js)) {
+            curAssets.js.push(js);
+          }
+        }
+      } else {
+        curAssets.js = newAssets.js;
+      }
+    }
+
+    if (newAssets.css) {
+      if (curAssets.css) {
+        for (const css of newAssets.css) {
+          if (!curAssets.css.includes(css)) {
+            curAssets.css.push(css);
+          }
+        }
+      } else {
+        curAssets.css = newAssets.css;
+      }
+    }
+  } else {
+    out.___flush = out.flush;
+    out.___end = out.end;
+    out.___renderAssets = renderAssets;
+    out.___assets = newAssets;
+    out.flush = outFlushOverride;
+    out.end = outEndOverride;
+  }
 
   marko_dist_runtime_helpers_render_tag__WEBPACK_IMPORTED_MODULE_2___default()(_test_marko__WEBPACK_IMPORTED_MODULE_0__["default"], input, out, _component, "0");
 
diff --git a/src/__tests__/fixtures/basic-template-plugin-custom-runtime-id/__snapshots__/webpack5/server--main.js b/src/__tests__/fixtures/basic-template-plugin-custom-runtime-id/__snapshots__/webpack5/server--main.js
index e6c86c8..2a8fb54 100644
--- a/src/__tests__/fixtures/basic-template-plugin-custom-runtime-id/__snapshots__/webpack5/server--main.js
+++ b/src/__tests__/fixtures/basic-template-plugin-custom-runtime-id/__snapshots__/webpack5/server--main.js
@@ -108,12 +108,41 @@ const _marko_componentType = "8XgZ/c27",
       _marko_component = {};
 _marko_template._ = marko_dist_runtime_components_renderer__WEBPACK_IMPORTED_MODULE_6___default()(function (input, out, _component, component, state) {
   out.global.runtimeId = "testruntime";
-  out.___flush = out.flush;
-  out.___end = out.end;
-  out.___renderAssets = renderAssets;
-  out.___assets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_2__.default.getAssets("test_8XgZ", out.global.buildName);
-  out.flush = outFlushOverride;
-  out.end = outEndOverride;
+  const curAssets = out.___assets;
+  const newAssets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_2__.default.getAssets("test_8XgZ", out.global.buildName);
+
+  if (curAssets) {
+    if (newAssets.js) {
+      if (curAssets.js) {
+        for (const js of newAssets.js) {
+          if (!curAssets.js.includes(js)) {
+            curAssets.js.push(js);
+          }
+        }
+      } else {
+        curAssets.js = newAssets.js;
+      }
+    }
+
+    if (newAssets.css) {
+      if (curAssets.css) {
+        for (const css of newAssets.css) {
+          if (!curAssets.css.includes(css)) {
+            curAssets.css.push(css);
+          }
+        }
+      } else {
+        curAssets.css = newAssets.css;
+      }
+    }
+  } else {
+    out.___flush = out.flush;
+    out.___end = out.end;
+    out.___renderAssets = renderAssets;
+    out.___assets = newAssets;
+    out.flush = outFlushOverride;
+    out.end = outEndOverride;
+  }
 
   marko_dist_runtime_helpers_render_tag__WEBPACK_IMPORTED_MODULE_3___default()(_test_marko__WEBPACK_IMPORTED_MODULE_1__.default, input, out, _component, "0");
 
diff --git a/src/__tests__/fixtures/basic-template-plugin/__snapshots__/webpack4/server--main.js b/src/__tests__/fixtures/basic-template-plugin/__snapshots__/webpack4/server--main.js
index bfae6ef..a02ec0f 100644
--- a/src/__tests__/fixtures/basic-template-plugin/__snapshots__/webpack4/server--main.js
+++ b/src/__tests__/fixtures/basic-template-plugin/__snapshots__/webpack4/server--main.js
@@ -121,12 +121,41 @@ function outEndOverride(data, encoding, callback) {
 const _marko_componentType = "r9oeuJMR",
       _marko_component = {};
 _marko_template._ = marko_dist_runtime_components_renderer__WEBPACK_IMPORTED_MODULE_5___default()(function (input, out, _component, component, state) {
-  out.___flush = out.flush;
-  out.___end = out.end;
-  out.___renderAssets = renderAssets;
-  out.___assets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_1__["default"].getAssets("test_r9oe", out.global.buildName);
-  out.flush = outFlushOverride;
-  out.end = outEndOverride;
+  const curAssets = out.___assets;
+  const newAssets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_1__["default"].getAssets("test_r9oe", out.global.buildName);
+
+  if (curAssets) {
+    if (newAssets.js) {
+      if (curAssets.js) {
+        for (const js of newAssets.js) {
+          if (!curAssets.js.includes(js)) {
+            curAssets.js.push(js);
+          }
+        }
+      } else {
+        curAssets.js = newAssets.js;
+      }
+    }
+
+    if (newAssets.css) {
+      if (curAssets.css) {
+        for (const css of newAssets.css) {
+          if (!curAssets.css.includes(css)) {
+            curAssets.css.push(css);
+          }
+        }
+      } else {
+        curAssets.css = newAssets.css;
+      }
+    }
+  } else {
+    out.___flush = out.flush;
+    out.___end = out.end;
+    out.___renderAssets = renderAssets;
+    out.___assets = newAssets;
+    out.flush = outFlushOverride;
+    out.end = outEndOverride;
+  }
 
   marko_dist_runtime_helpers_render_tag__WEBPACK_IMPORTED_MODULE_2___default()(_test_marko__WEBPACK_IMPORTED_MODULE_0__["default"], input, out, _component, "0");
 
diff --git a/src/__tests__/fixtures/basic-template-plugin/__snapshots__/webpack5/server--main.js b/src/__tests__/fixtures/basic-template-plugin/__snapshots__/webpack5/server--main.js
index 465a02a..1f5e227 100644
--- a/src/__tests__/fixtures/basic-template-plugin/__snapshots__/webpack5/server--main.js
+++ b/src/__tests__/fixtures/basic-template-plugin/__snapshots__/webpack5/server--main.js
@@ -107,12 +107,41 @@ function outEndOverride(data, encoding, callback) {
 const _marko_componentType = "r9oeuJMR",
       _marko_component = {};
 _marko_template._ = marko_dist_runtime_components_renderer__WEBPACK_IMPORTED_MODULE_6___default()(function (input, out, _component, component, state) {
-  out.___flush = out.flush;
-  out.___end = out.end;
-  out.___renderAssets = renderAssets;
-  out.___assets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_2__.default.getAssets("test_r9oe", out.global.buildName);
-  out.flush = outFlushOverride;
-  out.end = outEndOverride;
+  const curAssets = out.___assets;
+  const newAssets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_2__.default.getAssets("test_r9oe", out.global.buildName);
+
+  if (curAssets) {
+    if (newAssets.js) {
+      if (curAssets.js) {
+        for (const js of newAssets.js) {
+          if (!curAssets.js.includes(js)) {
+            curAssets.js.push(js);
+          }
+        }
+      } else {
+        curAssets.js = newAssets.js;
+      }
+    }
+
+    if (newAssets.css) {
+      if (curAssets.css) {
+        for (const css of newAssets.css) {
+          if (!curAssets.css.includes(css)) {
+            curAssets.css.push(css);
+          }
+        }
+      } else {
+        curAssets.css = newAssets.css;
+      }
+    }
+  } else {
+    out.___flush = out.flush;
+    out.___end = out.end;
+    out.___renderAssets = renderAssets;
+    out.___assets = newAssets;
+    out.flush = outFlushOverride;
+    out.end = outEndOverride;
+  }
 
   marko_dist_runtime_helpers_render_tag__WEBPACK_IMPORTED_MODULE_3___default()(_test_marko__WEBPACK_IMPORTED_MODULE_1__.default, input, out, _component, "0");
 
diff --git a/src/__tests__/fixtures/multiple-entries-plugin/__snapshots__/webpack4/server--main.js b/src/__tests__/fixtures/multiple-entries-plugin/__snapshots__/webpack4/server--main.js
index 545199e..35dfd59 100644
--- a/src/__tests__/fixtures/multiple-entries-plugin/__snapshots__/webpack4/server--main.js
+++ b/src/__tests__/fixtures/multiple-entries-plugin/__snapshots__/webpack4/server--main.js
@@ -109,12 +109,41 @@ function outEndOverride(data, encoding, callback) {
 const _marko_componentType = "qMMCl8/W",
       _marko_component = {};
 _marko_template._ = marko_dist_runtime_components_renderer__WEBPACK_IMPORTED_MODULE_5___default()(function (input, out, _component, component, state) {
-  out.___flush = out.flush;
-  out.___end = out.end;
-  out.___renderAssets = renderAssets;
-  out.___assets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_1__["default"].getAssets("bar_qMMC", out.global.buildName);
-  out.flush = outFlushOverride;
-  out.end = outEndOverride;
+  const curAssets = out.___assets;
+  const newAssets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_1__["default"].getAssets("bar_qMMC", out.global.buildName);
+
+  if (curAssets) {
+    if (newAssets.js) {
+      if (curAssets.js) {
+        for (const js of newAssets.js) {
+          if (!curAssets.js.includes(js)) {
+            curAssets.js.push(js);
+          }
+        }
+      } else {
+        curAssets.js = newAssets.js;
+      }
+    }
+
+    if (newAssets.css) {
+      if (curAssets.css) {
+        for (const css of newAssets.css) {
+          if (!curAssets.css.includes(css)) {
+            curAssets.css.push(css);
+          }
+        }
+      } else {
+        curAssets.css = newAssets.css;
+      }
+    }
+  } else {
+    out.___flush = out.flush;
+    out.___end = out.end;
+    out.___renderAssets = renderAssets;
+    out.___assets = newAssets;
+    out.flush = outFlushOverride;
+    out.end = outEndOverride;
+  }
 
   marko_dist_runtime_helpers_render_tag__WEBPACK_IMPORTED_MODULE_2___default()(_bar_marko__WEBPACK_IMPORTED_MODULE_0__["default"], input, out, _component, "0");
 
@@ -266,12 +295,41 @@ function outEndOverride(data, encoding, callback) {
 const _marko_componentType = "FRgaW2aC",
       _marko_component = {};
 _marko_template._ = marko_dist_runtime_components_renderer__WEBPACK_IMPORTED_MODULE_5___default()(function (input, out, _component, component, state) {
-  out.___flush = out.flush;
-  out.___end = out.end;
-  out.___renderAssets = renderAssets;
-  out.___assets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_1__["default"].getAssets("foo_FRga", out.global.buildName);
-  out.flush = outFlushOverride;
-  out.end = outEndOverride;
+  const curAssets = out.___assets;
+  const newAssets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_1__["default"].getAssets("foo_FRga", out.global.buildName);
+
+  if (curAssets) {
+    if (newAssets.js) {
+      if (curAssets.js) {
+        for (const js of newAssets.js) {
+          if (!curAssets.js.includes(js)) {
+            curAssets.js.push(js);
+          }
+        }
+      } else {
+        curAssets.js = newAssets.js;
+      }
+    }
+
+    if (newAssets.css) {
+      if (curAssets.css) {
+        for (const css of newAssets.css) {
+          if (!curAssets.css.includes(css)) {
+            curAssets.css.push(css);
+          }
+        }
+      } else {
+        curAssets.css = newAssets.css;
+      }
+    }
+  } else {
+    out.___flush = out.flush;
+    out.___end = out.end;
+    out.___renderAssets = renderAssets;
+    out.___assets = newAssets;
+    out.flush = outFlushOverride;
+    out.end = outEndOverride;
+  }
 
   marko_dist_runtime_helpers_render_tag__WEBPACK_IMPORTED_MODULE_2___default()(_foo_marko__WEBPACK_IMPORTED_MODULE_0__["default"], input, out, _component, "0");
 
@@ -394,12 +452,41 @@ function outEndOverride(data, encoding, callback) {
 const _marko_componentType = "vyXF8r3F",
       _marko_component = {};
 _marko_template._ = marko_dist_runtime_components_renderer__WEBPACK_IMPORTED_MODULE_5___default()(function (input, out, _component, component, state) {
-  out.___flush = out.flush;
-  out.___end = out.end;
-  out.___renderAssets = renderAssets;
-  out.___assets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_1__["default"].getAssets("nested_vyXF", out.global.buildName);
-  out.flush = outFlushOverride;
-  out.end = outEndOverride;
+  const curAssets = out.___assets;
+  const newAssets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_1__["default"].getAssets("nested_vyXF", out.global.buildName);
+
+  if (curAssets) {
+    if (newAssets.js) {
+      if (curAssets.js) {
+        for (const js of newAssets.js) {
+          if (!curAssets.js.includes(js)) {
+            curAssets.js.push(js);
+          }
+        }
+      } else {
+        curAssets.js = newAssets.js;
+      }
+    }
+
+    if (newAssets.css) {
+      if (curAssets.css) {
+        for (const css of newAssets.css) {
+          if (!curAssets.css.includes(css)) {
+            curAssets.css.push(css);
+          }
+        }
+      } else {
+        curAssets.css = newAssets.css;
+      }
+    }
+  } else {
+    out.___flush = out.flush;
+    out.___end = out.end;
+    out.___renderAssets = renderAssets;
+    out.___assets = newAssets;
+    out.flush = outFlushOverride;
+    out.end = outEndOverride;
+  }
 
   marko_dist_runtime_helpers_render_tag__WEBPACK_IMPORTED_MODULE_2___default()(_template_marko__WEBPACK_IMPORTED_MODULE_0__["default"], input, out, _component, "0");
 
diff --git a/src/__tests__/fixtures/multiple-entries-plugin/__snapshots__/webpack5/server--main.js b/src/__tests__/fixtures/multiple-entries-plugin/__snapshots__/webpack5/server--main.js
index f9e7e3c..d7cb681 100644
--- a/src/__tests__/fixtures/multiple-entries-plugin/__snapshots__/webpack5/server--main.js
+++ b/src/__tests__/fixtures/multiple-entries-plugin/__snapshots__/webpack5/server--main.js
@@ -114,12 +114,41 @@ function outEndOverride(data, encoding, callback) {
 const _marko_componentType = "qMMCl8/W",
       _marko_component = {};
 _marko_template._ = marko_dist_runtime_components_renderer__WEBPACK_IMPORTED_MODULE_6___default()(function (input, out, _component, component, state) {
-  out.___flush = out.flush;
-  out.___end = out.end;
-  out.___renderAssets = renderAssets;
-  out.___assets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_2__.default.getAssets("bar_qMMC", out.global.buildName);
-  out.flush = outFlushOverride;
-  out.end = outEndOverride;
+  const curAssets = out.___assets;
+  const newAssets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_2__.default.getAssets("bar_qMMC", out.global.buildName);
+
+  if (curAssets) {
+    if (newAssets.js) {
+      if (curAssets.js) {
+        for (const js of newAssets.js) {
+          if (!curAssets.js.includes(js)) {
+            curAssets.js.push(js);
+          }
+        }
+      } else {
+        curAssets.js = newAssets.js;
+      }
+    }
+
+    if (newAssets.css) {
+      if (curAssets.css) {
+        for (const css of newAssets.css) {
+          if (!curAssets.css.includes(css)) {
+            curAssets.css.push(css);
+          }
+        }
+      } else {
+        curAssets.css = newAssets.css;
+      }
+    }
+  } else {
+    out.___flush = out.flush;
+    out.___end = out.end;
+    out.___renderAssets = renderAssets;
+    out.___assets = newAssets;
+    out.flush = outFlushOverride;
+    out.end = outEndOverride;
+  }
 
   marko_dist_runtime_helpers_render_tag__WEBPACK_IMPORTED_MODULE_3___default()(_bar_marko__WEBPACK_IMPORTED_MODULE_1__.default, input, out, _component, "0");
 
@@ -277,12 +306,41 @@ function outEndOverride(data, encoding, callback) {
 const _marko_componentType = "FRgaW2aC",
       _marko_component = {};
 _marko_template._ = marko_dist_runtime_components_renderer__WEBPACK_IMPORTED_MODULE_6___default()(function (input, out, _component, component, state) {
-  out.___flush = out.flush;
-  out.___end = out.end;
-  out.___renderAssets = renderAssets;
-  out.___assets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_2__.default.getAssets("foo_FRga", out.global.buildName);
-  out.flush = outFlushOverride;
-  out.end = outEndOverride;
+  const curAssets = out.___assets;
+  const newAssets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_2__.default.getAssets("foo_FRga", out.global.buildName);
+
+  if (curAssets) {
+    if (newAssets.js) {
+      if (curAssets.js) {
+        for (const js of newAssets.js) {
+          if (!curAssets.js.includes(js)) {
+            curAssets.js.push(js);
+          }
+        }
+      } else {
+        curAssets.js = newAssets.js;
+      }
+    }
+
+    if (newAssets.css) {
+      if (curAssets.css) {
+        for (const css of newAssets.css) {
+          if (!curAssets.css.includes(css)) {
+            curAssets.css.push(css);
+          }
+        }
+      } else {
+        curAssets.css = newAssets.css;
+      }
+    }
+  } else {
+    out.___flush = out.flush;
+    out.___end = out.end;
+    out.___renderAssets = renderAssets;
+    out.___assets = newAssets;
+    out.flush = outFlushOverride;
+    out.end = outEndOverride;
+  }
 
   marko_dist_runtime_helpers_render_tag__WEBPACK_IMPORTED_MODULE_3___default()(_foo_marko__WEBPACK_IMPORTED_MODULE_1__.default, input, out, _component, "0");
 
@@ -409,12 +467,41 @@ function outEndOverride(data, encoding, callback) {
 const _marko_componentType = "vyXF8r3F",
       _marko_component = {};
 _marko_template._ = marko_dist_runtime_components_renderer__WEBPACK_IMPORTED_MODULE_6___default()(function (input, out, _component, component, state) {
-  out.___flush = out.flush;
-  out.___end = out.end;
-  out.___renderAssets = renderAssets;
-  out.___assets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_2__.default.getAssets("nested_vyXF", out.global.buildName);
-  out.flush = outFlushOverride;
-  out.end = outEndOverride;
+  const curAssets = out.___assets;
+  const newAssets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_2__.default.getAssets("nested_vyXF", out.global.buildName);
+
+  if (curAssets) {
+    if (newAssets.js) {
+      if (curAssets.js) {
+        for (const js of newAssets.js) {
+          if (!curAssets.js.includes(js)) {
+            curAssets.js.push(js);
+          }
+        }
+      } else {
+        curAssets.js = newAssets.js;
+      }
+    }
+
+    if (newAssets.css) {
+      if (curAssets.css) {
+        for (const css of newAssets.css) {
+          if (!curAssets.css.includes(css)) {
+            curAssets.css.push(css);
+          }
+        }
+      } else {
+        curAssets.css = newAssets.css;
+      }
+    }
+  } else {
+    out.___flush = out.flush;
+    out.___end = out.end;
+    out.___renderAssets = renderAssets;
+    out.___assets = newAssets;
+    out.flush = outFlushOverride;
+    out.end = outEndOverride;
+  }
 
   marko_dist_runtime_helpers_render_tag__WEBPACK_IMPORTED_MODULE_3___default()(_template_marko__WEBPACK_IMPORTED_MODULE_1__.default, input, out, _component, "0");
 
diff --git a/src/__tests__/fixtures/with-class-component-plugin-dynamic-bundle/__snapshots__/webpack4/server--main.js b/src/__tests__/fixtures/with-class-component-plugin-dynamic-bundle/__snapshots__/webpack4/server--main.js
index 6f90eea..f47049f 100644
--- a/src/__tests__/fixtures/with-class-component-plugin-dynamic-bundle/__snapshots__/webpack4/server--main.js
+++ b/src/__tests__/fixtures/with-class-component-plugin-dynamic-bundle/__snapshots__/webpack4/server--main.js
@@ -161,12 +161,41 @@ function outEndOverride(data, encoding, callback) {
 const _marko_componentType = "xbStr3Q2",
       _marko_component = {};
 _marko_template._ = marko_dist_runtime_components_renderer__WEBPACK_IMPORTED_MODULE_5___default()(function (input, out, _component, component, state) {
-  out.___flush = out.flush;
-  out.___end = out.end;
-  out.___renderAssets = renderAssets;
-  out.___assets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_1__["default"].getAssets("test_xbSt", out.global.buildName);
-  out.flush = outFlushOverride;
-  out.end = outEndOverride;
+  const curAssets = out.___assets;
+  const newAssets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_1__["default"].getAssets("test_xbSt", out.global.buildName);
+
+  if (curAssets) {
+    if (newAssets.js) {
+      if (curAssets.js) {
+        for (const js of newAssets.js) {
+          if (!curAssets.js.includes(js)) {
+            curAssets.js.push(js);
+          }
+        }
+      } else {
+        curAssets.js = newAssets.js;
+      }
+    }
+
+    if (newAssets.css) {
+      if (curAssets.css) {
+        for (const css of newAssets.css) {
+          if (!curAssets.css.includes(css)) {
+            curAssets.css.push(css);
+          }
+        }
+      } else {
+        curAssets.css = newAssets.css;
+      }
+    }
+  } else {
+    out.___flush = out.flush;
+    out.___end = out.end;
+    out.___renderAssets = renderAssets;
+    out.___assets = newAssets;
+    out.flush = outFlushOverride;
+    out.end = outEndOverride;
+  }
 
   marko_dist_runtime_helpers_render_tag__WEBPACK_IMPORTED_MODULE_2___default()(_test_marko__WEBPACK_IMPORTED_MODULE_0__["default"], input, out, _component, "0");
 
diff --git a/src/__tests__/fixtures/with-class-component-plugin-dynamic-bundle/__snapshots__/webpack5/server--main.js b/src/__tests__/fixtures/with-class-component-plugin-dynamic-bundle/__snapshots__/webpack5/server--main.js
index 38b352b..e847056 100644
--- a/src/__tests__/fixtures/with-class-component-plugin-dynamic-bundle/__snapshots__/webpack5/server--main.js
+++ b/src/__tests__/fixtures/with-class-component-plugin-dynamic-bundle/__snapshots__/webpack5/server--main.js
@@ -149,12 +149,41 @@ function outEndOverride(data, encoding, callback) {
 const _marko_componentType = "xbStr3Q2",
       _marko_component = {};
 _marko_template._ = marko_dist_runtime_components_renderer__WEBPACK_IMPORTED_MODULE_6___default()(function (input, out, _component, component, state) {
-  out.___flush = out.flush;
-  out.___end = out.end;
-  out.___renderAssets = renderAssets;
-  out.___assets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_2__.default.getAssets("test_xbSt", out.global.buildName);
-  out.flush = outFlushOverride;
-  out.end = outEndOverride;
+  const curAssets = out.___assets;
+  const newAssets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_2__.default.getAssets("test_xbSt", out.global.buildName);
+
+  if (curAssets) {
+    if (newAssets.js) {
+      if (curAssets.js) {
+        for (const js of newAssets.js) {
+          if (!curAssets.js.includes(js)) {
+            curAssets.js.push(js);
+          }
+        }
+      } else {
+        curAssets.js = newAssets.js;
+      }
+    }
+
+    if (newAssets.css) {
+      if (curAssets.css) {
+        for (const css of newAssets.css) {
+          if (!curAssets.css.includes(css)) {
+            curAssets.css.push(css);
+          }
+        }
+      } else {
+        curAssets.css = newAssets.css;
+      }
+    }
+  } else {
+    out.___flush = out.flush;
+    out.___end = out.end;
+    out.___renderAssets = renderAssets;
+    out.___assets = newAssets;
+    out.flush = outFlushOverride;
+    out.end = outEndOverride;
+  }
 
   marko_dist_runtime_helpers_render_tag__WEBPACK_IMPORTED_MODULE_3___default()(_test_marko__WEBPACK_IMPORTED_MODULE_1__.default, input, out, _component, "0");
 
diff --git a/src/__tests__/fixtures/with-class-component-plugin/__snapshots__/webpack4/server--main.js b/src/__tests__/fixtures/with-class-component-plugin/__snapshots__/webpack4/server--main.js
index 9598e45..f9583f2 100644
--- a/src/__tests__/fixtures/with-class-component-plugin/__snapshots__/webpack4/server--main.js
+++ b/src/__tests__/fixtures/with-class-component-plugin/__snapshots__/webpack4/server--main.js
@@ -159,12 +159,41 @@ function outEndOverride(data, encoding, callback) {
 const _marko_componentType = "ntnz89r6",
       _marko_component = {};
 _marko_template._ = marko_dist_runtime_components_renderer__WEBPACK_IMPORTED_MODULE_5___default()(function (input, out, _component, component, state) {
-  out.___flush = out.flush;
-  out.___end = out.end;
-  out.___renderAssets = renderAssets;
-  out.___assets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_1__["default"].getAssets("test_ntnz", out.global.buildName);
-  out.flush = outFlushOverride;
-  out.end = outEndOverride;
+  const curAssets = out.___assets;
+  const newAssets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_1__["default"].getAssets("test_ntnz", out.global.buildName);
+
+  if (curAssets) {
+    if (newAssets.js) {
+      if (curAssets.js) {
+        for (const js of newAssets.js) {
+          if (!curAssets.js.includes(js)) {
+            curAssets.js.push(js);
+          }
+        }
+      } else {
+        curAssets.js = newAssets.js;
+      }
+    }
+
+    if (newAssets.css) {
+      if (curAssets.css) {
+        for (const css of newAssets.css) {
+          if (!curAssets.css.includes(css)) {
+            curAssets.css.push(css);
+          }
+        }
+      } else {
+        curAssets.css = newAssets.css;
+      }
+    }
+  } else {
+    out.___flush = out.flush;
+    out.___end = out.end;
+    out.___renderAssets = renderAssets;
+    out.___assets = newAssets;
+    out.flush = outFlushOverride;
+    out.end = outEndOverride;
+  }
 
   marko_dist_runtime_helpers_render_tag__WEBPACK_IMPORTED_MODULE_2___default()(_test_marko__WEBPACK_IMPORTED_MODULE_0__["default"], input, out, _component, "0");
 
diff --git a/src/__tests__/fixtures/with-class-component-plugin/__snapshots__/webpack5/server--main.js b/src/__tests__/fixtures/with-class-component-plugin/__snapshots__/webpack5/server--main.js
index fb8da93..aa61dfb 100644
--- a/src/__tests__/fixtures/with-class-component-plugin/__snapshots__/webpack5/server--main.js
+++ b/src/__tests__/fixtures/with-class-component-plugin/__snapshots__/webpack5/server--main.js
@@ -147,12 +147,41 @@ function outEndOverride(data, encoding, callback) {
 const _marko_componentType = "ntnz89r6",
       _marko_component = {};
 _marko_template._ = marko_dist_runtime_components_renderer__WEBPACK_IMPORTED_MODULE_6___default()(function (input, out, _component, component, state) {
-  out.___flush = out.flush;
-  out.___end = out.end;
-  out.___renderAssets = renderAssets;
-  out.___assets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_2__.default.getAssets("test_ntnz", out.global.buildName);
-  out.flush = outFlushOverride;
-  out.end = outEndOverride;
+  const curAssets = out.___assets;
+  const newAssets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_2__.default.getAssets("test_ntnz", out.global.buildName);
+
+  if (curAssets) {
+    if (newAssets.js) {
+      if (curAssets.js) {
+        for (const js of newAssets.js) {
+          if (!curAssets.js.includes(js)) {
+            curAssets.js.push(js);
+          }
+        }
+      } else {
+        curAssets.js = newAssets.js;
+      }
+    }
+
+    if (newAssets.css) {
+      if (curAssets.css) {
+        for (const css of newAssets.css) {
+          if (!curAssets.css.includes(css)) {
+            curAssets.css.push(css);
+          }
+        }
+      } else {
+        curAssets.css = newAssets.css;
+      }
+    }
+  } else {
+    out.___flush = out.flush;
+    out.___end = out.end;
+    out.___renderAssets = renderAssets;
+    out.___assets = newAssets;
+    out.flush = outFlushOverride;
+    out.end = outEndOverride;
+  }
 
   marko_dist_runtime_helpers_render_tag__WEBPACK_IMPORTED_MODULE_3___default()(_test_marko__WEBPACK_IMPORTED_MODULE_1__.default, input, out, _component, "0");
 
diff --git a/src/__tests__/fixtures/with-public-path/__snapshots__/webpack4/server--main.js b/src/__tests__/fixtures/with-public-path/__snapshots__/webpack4/server--main.js
index 8832f20..0d6faae 100644
--- a/src/__tests__/fixtures/with-public-path/__snapshots__/webpack4/server--main.js
+++ b/src/__tests__/fixtures/with-public-path/__snapshots__/webpack4/server--main.js
@@ -119,12 +119,41 @@ function outEndOverride(data, encoding, callback) {
 const _marko_componentType = "xGHmCIBi",
       _marko_component = {};
 _marko_template._ = marko_dist_runtime_components_renderer__WEBPACK_IMPORTED_MODULE_5___default()(function (input, out, _component, component, state) {
-  out.___flush = out.flush;
-  out.___end = out.end;
-  out.___renderAssets = renderAssets;
-  out.___assets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_1__["default"].getAssets("test_xGHm", out.global.buildName);
-  out.flush = outFlushOverride;
-  out.end = outEndOverride;
+  const curAssets = out.___assets;
+  const newAssets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_1__["default"].getAssets("test_xGHm", out.global.buildName);
+
+  if (curAssets) {
+    if (newAssets.js) {
+      if (curAssets.js) {
+        for (const js of newAssets.js) {
+          if (!curAssets.js.includes(js)) {
+            curAssets.js.push(js);
+          }
+        }
+      } else {
+        curAssets.js = newAssets.js;
+      }
+    }
+
+    if (newAssets.css) {
+      if (curAssets.css) {
+        for (const css of newAssets.css) {
+          if (!curAssets.css.includes(css)) {
+            curAssets.css.push(css);
+          }
+        }
+      } else {
+        curAssets.css = newAssets.css;
+      }
+    }
+  } else {
+    out.___flush = out.flush;
+    out.___end = out.end;
+    out.___renderAssets = renderAssets;
+    out.___assets = newAssets;
+    out.flush = outFlushOverride;
+    out.end = outEndOverride;
+  }
 
   marko_dist_runtime_helpers_render_tag__WEBPACK_IMPORTED_MODULE_2___default()(_test_marko__WEBPACK_IMPORTED_MODULE_0__["default"], input, out, _component, "0");
 
diff --git a/src/__tests__/fixtures/with-public-path/__snapshots__/webpack5/server--main.js b/src/__tests__/fixtures/with-public-path/__snapshots__/webpack5/server--main.js
index 7c38e31..590b837 100644
--- a/src/__tests__/fixtures/with-public-path/__snapshots__/webpack5/server--main.js
+++ b/src/__tests__/fixtures/with-public-path/__snapshots__/webpack5/server--main.js
@@ -105,12 +105,41 @@ function outEndOverride(data, encoding, callback) {
 const _marko_componentType = "xGHmCIBi",
       _marko_component = {};
 _marko_template._ = marko_dist_runtime_components_renderer__WEBPACK_IMPORTED_MODULE_6___default()(function (input, out, _component, component, state) {
-  out.___flush = out.flush;
-  out.___end = out.end;
-  out.___renderAssets = renderAssets;
-  out.___assets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_2__.default.getAssets("test_xGHm", out.global.buildName);
-  out.flush = outFlushOverride;
-  out.end = outEndOverride;
+  const curAssets = out.___assets;
+  const newAssets = _marko_webpack_loader_manifest__WEBPACK_IMPORTED_MODULE_2__.default.getAssets("test_xGHm", out.global.buildName);
+
+  if (curAssets) {
+    if (newAssets.js) {
+      if (curAssets.js) {
+        for (const js of newAssets.js) {
+          if (!curAssets.js.includes(js)) {
+            curAssets.js.push(js);
+          }
+        }
+      } else {
+        curAssets.js = newAssets.js;
+      }
+    }
+
+    if (newAssets.css) {
+      if (curAssets.css) {
+        for (const css of newAssets.css) {
+          if (!curAssets.css.includes(css)) {
+            curAssets.css.push(css);
+          }
+        }
+      } else {
+        curAssets.css = newAssets.css;
+      }
+    }
+  } else {
+    out.___flush = out.flush;
+    out.___end = out.end;
+    out.___renderAssets = renderAssets;
+    out.___assets = newAssets;
+    out.flush = outFlushOverride;
+    out.end = outEndOverride;
+  }
 
   marko_dist_runtime_helpers_render_tag__WEBPACK_IMPORTED_MODULE_3___default()(_test_marko__WEBPACK_IMPORTED_MODULE_1__.default, input, out, _component, "0");
 
diff --git a/src/loader/get-asset-code.ts b/src/loader/get-asset-code.ts
index 7ef29f2..3f9c2f1 100644
--- a/src/loader/get-asset-code.ts
+++ b/src/loader/get-asset-code.ts
@@ -57,19 +57,50 @@ static function outEndOverride(data, encoding, callback) {
   this.end(data, encoding, callback);
 }
 
-${
-  runtimeId === undefined
-    ? ""
-    : `$ out.global.runtimeId = ${JSON.stringify(runtimeId)};`
-}
-$ out.___flush = out.flush;
-$ out.___end = out.end;
-$ out.___renderAssets = renderAssets;
-$ out.___assets = manifest.getAssets(${JSON.stringify(
+$ {
+  ${
+    runtimeId === undefined
+      ? ""
+      : `out.global.runtimeId = ${JSON.stringify(runtimeId)};`
+  }
+  const curAssets = out.___assets;
+  const newAssets = manifest.getAssets(${JSON.stringify(
     moduleName(resourcePath)
   )}, out.global.buildName);
-$ out.flush = outFlushOverride;
-$ out.end = outEndOverride;
+
+  if (curAssets) {
+    if (newAssets.js) {
+      if (curAssets.js) {
+        for (const js of newAssets.js) {
+          if (!curAssets.js.includes(js)) {
+            curAssets.js.push(js);
+          }
+        }
+      } else {
+        curAssets.js = newAssets.js;
+      }
+    }
+
+    if (newAssets.css) {
+      if (curAssets.css) {
+        for (const css of newAssets.css) {
+          if (!curAssets.css.includes(css)) {
+            curAssets.css.push(css);
+          }
+        }
+      } else {
+        curAssets.css = newAssets.css;
+      }
+    }
+  } else {
+    out.___flush = out.flush;
+    out.___end = out.end;
+    out.___renderAssets = renderAssets;
+    out.___assets = newAssets;
+    out.flush = outFlushOverride;
+    out.end = outEndOverride;
+  }
+}
 
 <\${template} ...input/>
 <init-components/>