diff --git a/ivtest/ivltests/module_output_port_list_def.v b/ivtest/ivltests/module_output_port_list_def.v
index d40f453fe..6777e5b31 100644
--- a/ivtest/ivltests/module_output_port_list_def.v
+++ b/ivtest/ivltests/module_output_port_list_def.v
@@ -2,7 +2,7 @@
 // output port declaration list.
 
 module M (
-  output [31:0] x = 1, y = 2
+  output reg [31:0] x = 1, y = 2
 );
 
   `define check(val, exp) \