Index: generic/tclVar.c
===================================================================
RCS file: /cvsroot/tcl/tcl/generic/tclVar.c,v
retrieving revision 1.176
diff -u -r1.176 tclVar.c
--- generic/tclVar.c	10 Feb 2009 23:08:57 -0000	1.176
+++ generic/tclVar.c	4 Mar 2009 16:32:24 -0000
@@ -2555,7 +2555,7 @@
 
 	    varValuePtr = TclPtrSetVar(interp, varPtr, arrayPtr, objv[1],
 		    NULL, objv[i], TCL_APPEND_VALUE|TCL_LEAVE_ERR_MSG, -1);
-	    if (varValuePtr == NULL) {
+	    if (varValuePtr == ((Interp *) interp)->emptyObjPtr) {
 		return TCL_ERROR;
 	    }
 	}
