diff --git a/src/codegen.c b/src/codegen.c
index 96b51840..8fbb40c0 100644
--- a/src/codegen.c
+++ b/src/codegen.c
@@ -1426,6 +1426,34 @@ __assign_codegen_kvar_defitem_subfields(codegen_kvar_defitem *kvdef)
 	}
 }
 
+/*
+ * equalVar - compares two Var nodes except for varnullingrels
+ *
+ * NOTE: Var-nodes in the reltarget of input-paths are not normalized
+ * to this level of GpuJoin, so it may have different varnullingrels
+ * even if they are identical Var-nodes. So, we should not use equal()
+ * here to compare Var-nodes.
+ */
+static inline bool
+equalVar(const void *__a, const void *__b)
+{
+	if (IsA(__a, Var) && IsA(__b, Var))
+	{
+		const Var  *a = __a;
+		const Var  *b = __b;
+
+		if (a->varno    == b->varno &&
+			a->varattno == b->varattno)
+		{
+			Assert(a->vartype   == b->vartype &&
+				   a->vartypmod == b->vartypmod &&
+				   a->varcollid == b->varcollid);
+			return true;
+		}
+	}
+	return false;
+}
+
 /*
  * lookup_input_varnode_defitem
  */
@@ -1464,7 +1492,7 @@ lookup_input_varnode_defitem(codegen_context *context,
 		resno = 1;
 		foreach (lc, target->exprs)
 		{
-			if (equal(var, lfirst(lc)))
+			if (equalVar(var, lfirst(lc)))
 				goto found;
 			resno++;
 		}
@@ -1478,7 +1506,7 @@ lookup_input_varnode_defitem(codegen_context *context,
 		if (kvdef->kv_depth == depth &&
 			kvdef->kv_resno == resno)
 		{
-			Assert(equal(var, kvdef->kv_expr));
+			Assert(equalVar(var, kvdef->kv_expr));
 			kvdef->kv_maxref = Max(kvdef->kv_maxref, curr_depth);
 			return kvdef;
 		}