diff --git a/svtools/source/control/ruler.cxx b/svtools/source/control/ruler.cxx
index 7ce2b5c9e14f..d1b94e6d72dc 100644
--- a/svtools/source/control/ruler.cxx
+++ b/svtools/source/control/ruler.cxx
@@ -193,6 +193,9 @@ ImplRulerData::~ImplRulerData()
 
 ImplRulerData& ImplRulerData::operator=( const ImplRulerData& rData )
 {
+    if( this == &rData )
+        return *this;
+
     delete[] pLines;
     delete[] pArrows;
     delete[] pBorders;