diff --git a/src/Mod/Sketcher/App/SketchObject.cpp b/src/Mod/Sketcher/App/SketchObject.cpp
index 37e81f3b13..d4f34362de 100644
--- a/src/Mod/Sketcher/App/SketchObject.cpp
+++ b/src/Mod/Sketcher/App/SketchObject.cpp
@@ -362,7 +362,7 @@ int SketchObject::setDatum(int ConstrId, double Datum)
     int err = solve();
 
     if (err)
-        newVals[ConstrId]->setValue(oldDatum);
+        this->Constraints.getValues()[ConstrId]->setValue(oldDatum); // newVals is a shell now
 
     return err;
 }