Index: generic/xotcl.c
===================================================================
diff -u -rc942f4e117d2aa3c8594702e0476a3f73a4147df -re5cee71c4fdd11860c1a897522c6d4202ebc64c4
--- generic/xotcl.c	(.../xotcl.c)	(revision c942f4e117d2aa3c8594702e0476a3f73a4147df)
+++ generic/xotcl.c	(.../xotcl.c)	(revision e5cee71c4fdd11860c1a897522c6d4202ebc64c4)
@@ -12393,11 +12393,16 @@
 
   result = ArgumentCheck(interp, value, paramPtr, &flags, &checkedData, &outObjPtr);
 
+  if (value != outObjPtr) {
+    Tcl_ResetResult(interp);
+  }
+
   if (flags & XOTCL_PC_MUST_DECR) {
     DECR_REF_COUNT(outObjPtr);
   }
-  
+
   Tcl_SetIntObj(Tcl_GetObjResult(interp), (result == TCL_OK));
+
   return TCL_OK;
 }