diff --git a/file2modulename.js b/file2modulename.js
index 784745cd43..1beb1fff37 100644
--- a/file2modulename.js
+++ b/file2modulename.js
@@ -1,8 +1,5 @@
 function file2moduleName(filePath) {
   return filePath
-    // module name should not include non word characters (e.g. '-')
-    // -> important for Dart
-    .replace(/[^\w.\/]/g, '_')
     // module name should be relative to `modules` and `tools` folder
     .replace(/.*\/modules\//, '')
     .replace(/.*\/tools\//, '')
diff --git a/tools/transpiler/src/outputgeneration/DartParseTreeWriter.js b/tools/transpiler/src/outputgeneration/DartParseTreeWriter.js
index b0e9690960..d60b5da845 100644
--- a/tools/transpiler/src/outputgeneration/DartParseTreeWriter.js
+++ b/tools/transpiler/src/outputgeneration/DartParseTreeWriter.js
@@ -20,7 +20,7 @@ import {ParseTreeWriter as JavaScriptParseTreeWriter, ObjectLiteralExpression} f
 export class DartParseTreeWriter extends JavaScriptParseTreeWriter {
   constructor(moduleName, outputPath) {
     super(outputPath);
-    this.libName = moduleName.replace(/\//g, '.');
+    this.libName = moduleName.replace(/\//g, '.').replace(/[^\w.\/]/g, '_');
   }
 
   // VARIABLES - types