diff --git a/includes/resourceloader/ResourceLoaderModule.php b/includes/resourceloader/ResourceLoaderModule.php
index 4cb6209d159..fbb271bef43 100644
--- a/includes/resourceloader/ResourceLoaderModule.php
+++ b/includes/resourceloader/ResourceLoaderModule.php
@@ -982,9 +982,9 @@ abstract class ResourceLoaderModule implements LoggerAwareInterface {
 					// By returning this as replacement for the actual script,
 					// we ensure modules are safe to load in a batch request,
 					// without causing other unrelated modules to break.
-					return 'mw.log.error(' .
-						Xml::encodeJsVar( 'JavaScript parse error: ' . $err->getMessage() ) .
-						');';
+					return 'mw.log.error(' . Xml::encodeJsVar(
+						'JavaScript parse error (scripts need to be valid ECMAScript 5): ' .
+						$err->getMessage() ) . ');';
 				}
 				return $contents;
 			}
diff --git a/tests/phpunit/includes/resourceloader/ResourceLoaderModuleTest.php b/tests/phpunit/includes/resourceloader/ResourceLoaderModuleTest.php
index 09577e91888..0915f40b8df 100644
--- a/tests/phpunit/includes/resourceloader/ResourceLoaderModuleTest.php
+++ b/tests/phpunit/includes/resourceloader/ResourceLoaderModuleTest.php
@@ -92,8 +92,8 @@ class ResourceLoaderModuleTest extends ResourceLoaderTestCase {
 		] );
 		$this->assertEquals(
 			'mw.log.error(' .
-				'"JavaScript parse error: Parse error: Unexpected token; ' .
-				'token } expected in file \'input\' on line 3"' .
+				'"JavaScript parse error (scripts need to be valid ECMAScript 5): ' .
+				'Parse error: Unexpected token; token } expected in file \'input\' on line 3"' .
 			');',
 			$module->getScript( $context ),
 			'Replace invalid syntax with error logging'