diff --git a/GCDWebServer/Core/GCDWebServer.h b/GCDWebServer/Core/GCDWebServer.h
index 674091e..727fb46 100644
--- a/GCDWebServer/Core/GCDWebServer.h
+++ b/GCDWebServer/Core/GCDWebServer.h
@@ -71,9 +71,10 @@ typedef void (^GCDWebServerAsyncProcessBlock)(__kindof GCDWebServerRequest* requ
 
 /**
  *  The GCDWebServerBuiltInLoggerBlock is used to override the built-in logger at runtime.
- *  The message parameter is the formatted log message with the logging level.
+ *  The block will be passed the log level and the log message, see setLogLevel for
+ *  documentation of the log levels for the built-in logger.
  */
-typedef void (^GCDWebServerBuiltInLoggerBlock)(NSString* _Nonnull message);
+typedef void (^GCDWebServerBuiltInLoggerBlock)(int level, NSString* _Nonnull message);
 
 /**
  *  The port used by the GCDWebServer (NSNumber / NSUInteger).
diff --git a/GCDWebServer/Core/GCDWebServer.m b/GCDWebServer/Core/GCDWebServer.m
index 344dfe2..1f1b70b 100644
--- a/GCDWebServer/Core/GCDWebServer.m
+++ b/GCDWebServer/Core/GCDWebServer.m
@@ -99,7 +99,7 @@ void GCDWebServerLogMessage(GCDWebServerLoggingLevel level, NSString* format, ..
     NSString* message = [[NSString alloc] initWithFormat:format arguments:arguments];
     va_end(arguments);
     if (_builtInLoggerBlock) {
-      _builtInLoggerBlock([NSString stringWithFormat:@"[%s] %s", levelNames[level], [message UTF8String]]);
+      _builtInLoggerBlock(level, message);
     } else {
       fprintf(stderr, "[%s] %s\n", levelNames[level], [message UTF8String]);
     }
@@ -1101,7 +1101,7 @@ static inline NSString* _EncodeBase64(NSString* string) {
 #if defined(__GCDWEBSERVER_LOGGING_FACILITY_BUILTIN__)
   _builtInLoggerBlock = block;
 #else
-  GWS_DCHECK(false) // Built-in logger must be enabled in order to override
+  GWS_DNOT_REACHED(); // Built-in logger must be enabled in order to override
 #endif
 }