diff --git a/libmariadb/mariadb_lib.c b/libmariadb/mariadb_lib.c
index 1065f30e..e05d3eea 100644
--- a/libmariadb/mariadb_lib.c
+++ b/libmariadb/mariadb_lib.c
@@ -1779,7 +1779,8 @@ mysql_select_db(MYSQL *mysql, const char *db)
 {
   int error;
 
-  if ((error=ma_simple_command(mysql, COM_INIT_DB,db,(uint) strlen(db),0,0)))
+  if ((error=ma_simple_command(mysql, COM_INIT_DB, db,
+                               db ? (uint) strlen(db) : 0,0,0)))
     return(error);
   free(mysql->db);
   mysql->db=strdup(db);