diff --git a/src/core/ngx_log.c b/src/core/ngx_log.c
index 531c860..7638b6a 100644
--- a/src/core/ngx_log.c
+++ b/src/core/ngx_log.c
@@ -47,7 +47,7 @@
 };
 
 static const char *debug_levels[] = {
-    "debug_core", "debug_alloc", "debug_event", "debug_http"
+    "debug_core", "debug_alloc", "debug_mutex", "debug_event", "debug_http"
 };
 
 
@@ -279,10 +279,6 @@
     ngx_log.file = &ngx_stderr;
     ngx_log.log_level = NGX_LOG_INFO;
 
-#if 0
-    /* STUB */ ngx_log.log_level = NGX_LOG_DEBUG;
-#endif
-
     return &ngx_log;
 }
 
@@ -303,10 +299,6 @@
     ngx_test_null(log, ngx_pcalloc(cycle->pool, sizeof(ngx_log_t)), NULL);
     ngx_test_null(log->file, ngx_conf_open_file(cycle, name), NULL);
 
-#if 0
-    /* STUB */ log->log_level = NGX_LOG_DEBUG | NGX_LOG_DEBUG_CORE | NGX_LOG_DEBUG_ALLOC | NGX_LOG_DEBUG_EVENT | NGX_LOG_DEBUG_HTTP;
-#endif
-
     return log;
 }
 
diff --git a/src/core/ngx_log.h b/src/core/ngx_log.h
index 87090dc..4765f3b 100644
--- a/src/core/ngx_log.h
+++ b/src/core/ngx_log.h
@@ -16,10 +16,11 @@
 #define NGX_LOG_INFO              7
 #define NGX_LOG_DEBUG             8
 
-#define NGX_LOG_DEBUG_CORE        0x10
-#define NGX_LOG_DEBUG_ALLOC       0x20
-#define NGX_LOG_DEBUG_EVENT       0x40
-#define NGX_LOG_DEBUG_HTTP        0x80
+#define NGX_LOG_DEBUG_CORE        0x010
+#define NGX_LOG_DEBUG_ALLOC       0x020
+#define NGX_LOG_DEBUG_MUTEX       0x040
+#define NGX_LOG_DEBUG_EVENT       0x080
+#define NGX_LOG_DEBUG_HTTP        0x100
 
 #define NGX_LOG_DEBUG_FIRST       NGX_LOG_DEBUG_CORE
 #define NGX_LOG_DEBUG_LAST        NGX_LOG_DEBUG_HTTP