--- op.c.orig   Mon Dec 17 13:51:32 2001
+++ op.c        Mon Dec 17 13:55:47 2001
@@ -4073,7 +4073,7 @@
              case OP_SASSIGN:
                if (k1->op_type == OP_READDIR
                      || k1->op_type == OP_GLOB
-                     || (k1->op_type == OP_NULL && k1->op_targ == OP_NULL)
+                     || (k1->op_type == OP_NULL && k1->op_targ == OP_GLOB)
                      || k1->op_type == OP_EACH)
                    expr = newUNOP(OP_DEFINED, 0, expr);
                break;