diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 3a402c6e..dc47011e 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -15,3 +15,14 @@ jobs:
       - uses: ./
       - run: cd test-build && sbt run
         shell: bash
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v1
+      - run: yarn install
+      - run: yarn run build
+      - uses: ./
+        with:
+          java-version: graal-20.2.0=tgz+https://github.com/graalvm/graalvm-ce-builds/releases/download/vm-20.2.0/graalvm-ce-java11-linux-aarch64-20.2.0.tar.gz
+      - run: cd test-build && sbt run
+        shell: bash
diff --git a/README.md b/README.md
index dcb87b2a..e394f8f5 100644
--- a/README.md
+++ b/README.md
@@ -1,15 +1,16 @@
 # Setup Scala GitHub Action
 
-A GitHub Action to install Java via [Jabba](https://github.com/shyiko/jabba)
-and sbt.
+A GitHub Action to install Java via [Jabba](https://github.com/shyiko/jabba) and
+sbt.
 
 - Configurable Java version: supports OpenJDK, GraalVM, Zulu and any other Java
   version that's installable via Jabba.
 - The `sbt` command is installed using the
   [paulp/sbt-extras](https://github.com/paulp/sbt-extras/) launcher.
 - For faster startup, the `csbt` command is installed using the Coursier-based
-  [coursier/sbt-extras](https://github.com/coursier/sbt-extras/) launcher. This launcher
-  does not work with all builds, only use `csbt` if you know what you are doing.
+  [coursier/sbt-extras](https://github.com/coursier/sbt-extras/) launcher. This
+  launcher does not work with all builds, only use `csbt` if you know what you
+  are doing.
 - Cross-platform: works on Linux, macOS, Windows.
 
 ## Usage:
@@ -58,6 +59,8 @@ More Java version examples:
 - `graalvm@`: the latest GraalVM
 - `openjdk@1.14`: the latest OpenJDK 14 version
 - `zulu@1.11`: the latest Zulu OpenJDK 11
+- `graalvm@20.2.0=tgz+https://github.com/graalvm/graalvm-ce-builds/releases/download/vm-20.2.0/graalvm-ce-java11-linux-aarch64-20.2.0.tar.gz`:
+  custom Java version from a URL
 
 ## Tips and tricks
 
@@ -118,11 +121,12 @@ configure git to disable Windows line feeds.
 
 ### Faster checkout of big repos
 
-Your repository can have a lot of commits, or branches with bulk resources.
-The v2 version of `actions/checkout` doesn't fetch a whole repo by default 
-that can speed up builds greatly. But an additional configuration can be 
-required to fetch tags up to some level of depth for some builds which check 
-binary compatibility with previous tagged release from the branch. 
+Your repository can have a lot of commits, or branches with bulk resources. The
+v2 version of `actions/checkout` doesn't fetch a whole repo by default that can
+speed up builds greatly. But an additional configuration can be required to
+fetch tags up to some level of depth for some builds which check binary
+compatibility with previous tagged release from the branch.
+
 ```diff
 +++ .github/workflows/ci.yml
   name: CI
diff --git a/src/install.ts b/src/install.ts
index c783274a..236196b8 100644
--- a/src/install.ts
+++ b/src/install.ts
@@ -49,29 +49,59 @@ function installJava(javaVersion: string, jabbaVersion: string) {
   shell.set("-ev");
   shell.exec(`curl -sL -o ${jabba} ${jabbaUrl}`, { silent: true });
   shell.chmod(755, jabba);
-  const toInstall = shell
-    .exec(`${jabba} ls-remote`)
-    .grep(javaVersion)
-    .head({ "-n": 1 })
-    .stdout.trim();
-  if (!toInstall) {
-    core.setFailed(`Couldn't find Java ${javaVersion}. To fix this problem, run 'jabba ls-remote' to see the list of valid Java versions.`);
-    return;
-  }
-  console.log(`Installing ${toInstall}`);
-  const result = shell.exec(`${jabba} install ${toInstall}`);
+  const jabbaInstall = javaVersion.includes("=")
+    ? installJavaByExactVersion(javaVersion)
+    : installJavaByFuzzyVersion(jabba, javaVersion);
+  if (!jabbaInstall) return;
+  console.log(`Installing ${jabbaInstall.name}`);
+  const result = shell.exec(`${jabba} install ${jabbaInstall.install}`);
   if (result.code > 0) {
-    core.setFailed(`Failed to install Java ${javaVersion}, Jabba stderr: ${result.stderr}`);
+    core.setFailed(
+      `Failed to install Java ${javaVersion}, Jabba stderr: ${result.stderr}`
+    );
     return;
   }
   const javaHome = shell
-    .exec(`${jabba} which --home ${toInstall}`)
+    .exec(`${jabba} which --home ${jabbaInstall.name}`)
     .stdout.trim();
   core.exportVariable("JAVA_HOME", javaHome);
   core.addPath(path.join(javaHome, "bin"));
   core.endGroup();
 }
 
+interface JabbaInstall {
+  name: string;
+  install: string;
+}
+
+function installJavaByFuzzyVersion(
+  jabba: string,
+  javaVersion: string
+): JabbaInstall | undefined {
+  const toInstall = shell
+    .exec(`${jabba} ls-remote`)
+    .grep(javaVersion)
+    .head({ "-n": 1 })
+    .stdout.trim();
+  if (!toInstall) {
+    core.setFailed(
+      `Couldn't find Java ${javaVersion}. To fix this problem, run 'jabba ls-remote' to see the list of valid Java versions.`
+    );
+    return;
+  }
+  return {
+    name: toInstall,
+    install: toInstall,
+  };
+}
+
+function installJavaByExactVersion(javaVersion: string): JabbaInstall {
+  return {
+    name: javaVersion.split("=")[0],
+    install: javaVersion,
+  };
+}
+
 function installSbt() {
   core.startGroup("Install sbt");
   core.addPath(bin);