diff --git a/define.go b/define.go
index f2c282e..f35c7a3 100644
--- a/define.go
+++ b/define.go
@@ -93,19 +93,19 @@ func log(loggerInstance *zap.Logger, f string, message string, fieldList []zap.F
 		return
 	}
 	switch f {
-	case "info":
+	case logFuncInfo:
 		loggerInstance.Info(message, fieldList...)
-	case "warn":
+	case logFuncWarn:
 		loggerInstance.Warn(message, fieldList...)
-	case "error":
+	case logFuncError:
 		loggerInstance.Error(message, fieldList...)
-	case "dpanic":
+	case logFuncDPanic:
 		loggerInstance.DPanic(message, fieldList...)
-	case "panic":
+	case logFuncPanic:
 		loggerInstance.Panic(message, fieldList...)
-	case "fatal":
+	case logFuncFatal:
 		loggerInstance.Fatal(message, fieldList...)
-	case "debug":
+	case logFuncDebug:
 		fallthrough
 	default:
 		loggerInstance.Debug(message, fieldList...)