diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index 6ce4efea118..cd704987347 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -1406,6 +1406,10 @@ get_relation_constraints(PlannerInfo *root,
 
 			cexpr = stringToNode(constr->check[i].ccbin);
 
+			/* Fix Vars to have the desired varno */
+			if (varno != 1)
+				ChangeVarNodes(cexpr, 1, varno, 0);
+
 			/*
 			 * Run each expression through const-simplification and
 			 * canonicalization.  This is not just an optimization, but is
@@ -1420,10 +1424,6 @@ get_relation_constraints(PlannerInfo *root,
 
 			cexpr = (Node *) canonicalize_qual((Expr *) cexpr, true);
 
-			/* Fix Vars to have the desired varno */
-			if (varno != 1)
-				ChangeVarNodes(cexpr, 1, varno, 0);
-
 			/*
 			 * Finally, convert to implicit-AND format (that is, a List) and
 			 * append the resulting item(s) to our output list.