diff --git a/vcl/source/control/field.cxx b/vcl/source/control/field.cxx
index bd03aadfd947..18d4d881e1a1 100644
--- a/vcl/source/control/field.cxx
+++ b/vcl/source/control/field.cxx
@@ -176,7 +176,7 @@ static bool ImplNumericGetValue( const OUString& rStr, sal_Int64& rValue,
     if ( aStr1.isEmpty() )
         aStr1 = "0";
     if ( bNegative )
-        aStr1 = "-" + aStr1;
+        aStr1.insert(0, "-");
 
     // prune and round fraction
     bool bRound = false;