diff --git a/tools/webpack/packages.js b/tools/webpack/packages.js
index 0a01380b0faed5..0d035e5377f709 100644
--- a/tools/webpack/packages.js
+++ b/tools/webpack/packages.js
@@ -143,9 +143,9 @@ module.exports = {
 		filename: './build/[name]/index.min.js',
 		path: join( __dirname, '..', '..' ),
 		devtoolModuleFilenameTemplate: ( info ) => {
-			if ( info.resourcePath.includes( '@wordpress' ) ) {
+			if ( info.resourcePath.includes( '/@wordpress/' ) ) {
 				const resourcePath =
-					info.resourcePath.split( '@wordpress' )[ 1 ];
+					info.resourcePath.split( '/@wordpress/' )[ 1 ];
 				return `../../packages/${ resourcePath }`;
 			}
 			return `webpack://${ info.namespace }/${ info.resourcePath }`;