diff --git a/src/backend/nodes/params.c b/src/backend/nodes/params.c
index d7d513e..7eb94d6 100644
--- a/src/backend/nodes/params.c
+++ b/src/backend/nodes/params.c
@@ -62,7 +62,7 @@ copyParamList(ParamListInfo from)
 
 		/* Ignore parameters we don't need, to save cycles and space. */
 		if (retval->paramMask != NULL &&
-			!bms_is_member(i, retval->paramMask))
+			!bms_is_member(i, from->paramMask))
 		{
 			nprm->value = (Datum) 0;
 			nprm->isnull = true;