diff --git a/SWIG/Lib/tcl/tclrun.swg b/SWIG/Lib/tcl/tclrun.swg
index 040f40980..1904f7fb4 100644
--- a/SWIG/Lib/tcl/tclrun.swg
+++ b/SWIG/Lib/tcl/tclrun.swg
@@ -133,7 +133,7 @@ SWIG_Tcl_ConvertPtrFromString(Tcl_Interp *interp, const char *c, void **ptr, swi
   c++;
   c = SWIG_UnpackData(c,ptr,sizeof(void *));
   if (ty) {
-    tc = SWIG_TypeCheck(c,ty);
+    tc = c ? SWIG_TypeCheck(c,ty) : 0;
     if (!tc) {
       return SWIG_ERROR;
     }