diff --git a/lib/compress.js b/lib/compress.js
index ae7dc359..66b7f037 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -4862,7 +4862,7 @@ merge(Compressor.prototype, {
         if (compressor.option("comparisons") &&
             (self.operator == "==" || self.operator == "!=") &&
             is_undefined(self.left, compressor)) {
-            self.left = make_node_from_constant(null, self.left);
+            self.left = make_node(AST_Null, self.left);
         }
         if (self.operator == "+" && compressor.in_boolean_context()) {
             var ll = self.left.evaluate(compressor);