diff --git a/dist/index.js b/dist/index.js
index 36a56bb..aed138a 100644
Binary files a/dist/index.js and b/dist/index.js differ
diff --git a/src/installer.ts b/src/installer.ts
index 7a8feae..29b0d89 100644
--- a/src/installer.ts
+++ b/src/installer.ts
@@ -87,6 +87,10 @@ export async function getJava(
   }
 
   let extendedJavaHome = 'JAVA_HOME_' + version + '_' + arch;
+  // For portability reasons environment variables should only consist of
+  // uppercase letters, digits, and the underscore. Therefore we convert
+  // the extendedJavaHome variable to upper case and replace '.' symbols and
+  // any other non-alphanumeric characters with an underscore.
   extendedJavaHome = extendedJavaHome.toUpperCase().replace(/[^0-9A-Z_]/g, '_');
   core.exportVariable('JAVA_HOME', toolPath);
   core.exportVariable(extendedJavaHome, toolPath);