diff --git a/src/core/qgsdatadefined.h b/src/core/qgsdatadefined.h
index 96fef077ed6..9a47deb52e1 100644
--- a/src/core/qgsdatadefined.h
+++ b/src/core/qgsdatadefined.h
@@ -63,7 +63,7 @@ class CORE_EXPORT QgsDataDefined
      * @param string field reference or an expression, can be empty
      * @note added in QGIS 2.9
      */
-    explicit QgsDataDefined( const QString& string );
+    QgsDataDefined( const QString& string );
 
     /**
      * Copy constructor. Note that copies of data defined objects with expressions