diff --git a/contrib/dblink/dblink.c b/contrib/dblink/dblink.c
index 276c7e1..a067309 100644
--- a/contrib/dblink/dblink.c
+++ b/contrib/dblink/dblink.c
@@ -2083,6 +2083,11 @@ get_tuple_of_interest(Oid relid, int2vector *pkattnums, int16 pknumatts, char **
 		/* internal error */
 		elog(ERROR, "SPI connect failure - returned %d", ret);
 
+	if (pknumatts > tupdesc->natts)
+		ereport(ERROR,
+				(errcode(ERRCODE_SYNTAX_ERROR),
+				 errmsg("statement has more expression then specified relation")));
+
 	/*
 	 * Build sql statement to look up tuple of interest Use src_pkattvals as
 	 * the criteria.