diff --git a/src/index.js b/src/index.js
index 451415b3..c27da884 100644
--- a/src/index.js
+++ b/src/index.js
@@ -479,7 +479,7 @@ class MiniCssExtractPlugin {
               `${webpack.RuntimeGlobals.require}.miniCssF`,
               (referencedChunk) => {
                 if (!referencedChunk.contentHash[MODULE_TYPE]) {
-                  return '';
+                  return false;
                 }
 
                 return referencedChunk.canBeInitial()
diff --git a/test/cases/hmr/expected/webpack-5/main.js b/test/cases/hmr/expected/webpack-5/main.js
index 3cc77dda..83afefff 100644
--- a/test/cases/hmr/expected/webpack-5/main.js
+++ b/test/cases/hmr/expected/webpack-5/main.js
@@ -358,7 +358,7 @@ module.exports = function (urlString) {
 /******/ 		// This function allow to reference all chunks
 /******/ 		__webpack_require__.miniCssF = (chunkId) => {
 /******/ 			// return url for filenames based on template
-/******/ 			return "" + "main" + ".css";
+/******/ 			return undefined;
 /******/ 		};
 /******/ 	})();
 /******/ 	
diff --git a/test/cases/hmr/webpack.config.js b/test/cases/hmr/webpack.config.js
index f21d6bb8..c64ce9ea 100644
--- a/test/cases/hmr/webpack.config.js
+++ b/test/cases/hmr/webpack.config.js
@@ -4,6 +4,7 @@ import Self from '../../../src';
 
 module.exports = {
   entry: './index.css',
+  mode: 'development',
   module: {
     rules: [
       {
diff --git a/test/cases/insert-function/expected/webpack-5/main.js b/test/cases/insert-function/expected/webpack-5/main.js
index e273ce62..f0ab3061 100644
--- a/test/cases/insert-function/expected/webpack-5/main.js
+++ b/test/cases/insert-function/expected/webpack-5/main.js
@@ -54,10 +54,8 @@
 /******/ 	(() => {
 /******/ 		// This function allow to reference all chunks
 /******/ 		__webpack_require__.miniCssF = (chunkId) => {
-/******/ 			// return url for filenames not based on template
-/******/ 			if (chunkId === 1) return "1.css";
 /******/ 			// return url for filenames based on template
-/******/ 			return "" + "main" + ".css";
+/******/ 			return "" + chunkId + ".css";
 /******/ 		};
 /******/ 	})();
 /******/ 	
diff --git a/test/cases/insert-string/expected/webpack-5/main.js b/test/cases/insert-string/expected/webpack-5/main.js
index 21fd7a79..581022c8 100644
--- a/test/cases/insert-string/expected/webpack-5/main.js
+++ b/test/cases/insert-string/expected/webpack-5/main.js
@@ -54,10 +54,8 @@
 /******/ 	(() => {
 /******/ 		// This function allow to reference all chunks
 /******/ 		__webpack_require__.miniCssF = (chunkId) => {
-/******/ 			// return url for filenames not based on template
-/******/ 			if (chunkId === 1) return "1.css";
 /******/ 			// return url for filenames based on template
-/******/ 			return "" + "main" + ".css";
+/******/ 			return "" + chunkId + ".css";
 /******/ 		};
 /******/ 	})();
 /******/ 	
diff --git a/test/cases/insert-undefined/expected/webpack-5/main.js b/test/cases/insert-undefined/expected/webpack-5/main.js
index 2d7ef200..ffd6d783 100644
--- a/test/cases/insert-undefined/expected/webpack-5/main.js
+++ b/test/cases/insert-undefined/expected/webpack-5/main.js
@@ -54,10 +54,8 @@
 /******/ 	(() => {
 /******/ 		// This function allow to reference all chunks
 /******/ 		__webpack_require__.miniCssF = (chunkId) => {
-/******/ 			// return url for filenames not based on template
-/******/ 			if (chunkId === 1) return "1.css";
 /******/ 			// return url for filenames based on template
-/******/ 			return "" + "main" + ".css";
+/******/ 			return "" + chunkId + ".css";
 /******/ 		};
 /******/ 	})();
 /******/