diff --git a/m_config.c b/m_config.c
index f669cd23bb..53257f57cb 100644
--- a/m_config.c
+++ b/m_config.c
@@ -214,8 +214,10 @@ m_config_parse_option(m_config_t *config, char* arg, char* param,int set) {
 #endif
 
   co = m_config_get_co(config,arg);
-  if(!co)
+  if(!co){
+    mp_msg(MSGT_CFGPARSER, MSGL_ERR,"Unknown option: %s\n",arg);
     return M_OPT_UNKNOW;
+  }
 
 #ifdef MP_DEBUG
   // This is the only mandatory function