diff --git a/src/STEPCAFControl/STEPCAFControl_Reader.cxx b/src/STEPCAFControl/STEPCAFControl_Reader.cxx
index 07ba7d3d93..a1234d9d1d 100644
--- a/src/STEPCAFControl/STEPCAFControl_Reader.cxx
+++ b/src/STEPCAFControl/STEPCAFControl_Reader.cxx
@@ -3074,7 +3074,8 @@ TDF_Label STEPCAFControl_Reader::createGDTObjectInXCAF(const Handle(Standard_Tra
     {
       TDF_Label aShL;
       aSTool->Search(aSh, aShL, Standard_True, Standard_True, Standard_True);
-      aShLS1.Append(aShL);
+      if (!aShL.IsNull())
+        aShLS1.Append(aShL);
     }
   }
   if (!aSeqRI2.IsEmpty())
@@ -3092,7 +3093,8 @@ TDF_Label STEPCAFControl_Reader::createGDTObjectInXCAF(const Handle(Standard_Tra
       {
         TDF_Label aShL;
         aSTool->Search(aSh, aShL, Standard_True, Standard_True, Standard_True);
-        aShLS2.Append(aShL);
+        if (!aShL.IsNull())
+          aShLS2.Append(aShL);
       }
     }
   }
diff --git a/src/StepVisual/StepVisual_PresentationStyleAssignment.cxx b/src/StepVisual/StepVisual_PresentationStyleAssignment.cxx
index f846b5dadd..0050f845c3 100644
--- a/src/StepVisual/StepVisual_PresentationStyleAssignment.cxx
+++ b/src/StepVisual/StepVisual_PresentationStyleAssignment.cxx
@@ -45,5 +45,5 @@ StepVisual_PresentationStyleSelect StepVisual_PresentationStyleAssignment::Style
 
 Standard_Integer StepVisual_PresentationStyleAssignment::NbStyles () const
 {
-	return styles->Length();
+	return styles.IsNull() ? 0 : styles->Length();
 }