diff --git a/contrib/postgres_fdw/deparse.c b/contrib/postgres_fdw/deparse.c
index c91f3a5..7446506 100644
--- a/contrib/postgres_fdw/deparse.c
+++ b/contrib/postgres_fdw/deparse.c
@@ -1644,9 +1644,9 @@ deparseColumnRef(StringInfo buf, int varno, int varattno, PlannerInfo *root,
 		 */
 		if (qualify_col)
 		{
-			appendStringInfoString(buf, "CASE WHEN ");
+			appendStringInfoString(buf, "CASE WHEN NOT ");
 			ADD_REL_QUALIFIER(buf, varno);
-			appendStringInfo(buf, "* IS NOT NULL THEN ");
+			appendStringInfo(buf, "* IS NULL THEN ");
 		}
 
 		appendStringInfoString(buf, "ROW(");