diff --git a/src/libs/qmljs/qmljsmodelmanagerinterface.cpp b/src/libs/qmljs/qmljsmodelmanagerinterface.cpp
index 1291b6525aa..a267f85e473 100644
--- a/src/libs/qmljs/qmljsmodelmanagerinterface.cpp
+++ b/src/libs/qmljs/qmljsmodelmanagerinterface.cpp
@@ -165,6 +165,7 @@ ModelManagerInterface::~ModelManagerInterface()
 static QHash<QString, Dialect> defaultLanguageMapping()
 {
     static QHash<QString, Dialect> res{
+        {QLatin1String("mjs"), Dialect::JavaScript},
         {QLatin1String("js"), Dialect::JavaScript},
         {QLatin1String("qml"), Dialect::Qml},
         {QLatin1String("qmltypes"), Dialect::QmlTypeInfo},