diff --git a/src/corelib/tools/qdatetime.cpp b/src/corelib/tools/qdatetime.cpp
index 2b006fe2d5..5b335de929 100644
--- a/src/corelib/tools/qdatetime.cpp
+++ b/src/corelib/tools/qdatetime.cpp
@@ -167,7 +167,7 @@ static int qt_monthNumberFromShortName(QStringRef shortName)
     }
     return -1;
 }
-int qt_monthNumberFromShortName(const QString &shortName)
+static int qt_monthNumberFromShortName(const QString &shortName)
 { return qt_monthNumberFromShortName(QStringRef(&shortName)); }
 
 static int fromShortMonthName(const QStringRef &monthName)