diff --git a/json_formatter.go b/json_formatter.go
index 098a21a..b951c89 100644
--- a/json_formatter.go
+++ b/json_formatter.go
@@ -97,7 +97,7 @@ func (f *JSONFormatter) Format(entry *Entry) ([]byte, error) {
 		if funcVal != "" {
 			data[f.FieldMap.resolve(FieldKeyFunc)] = funcVal
 		}
-		if fileVal != "" {
+		if fileVal != ":0" {
 			data[f.FieldMap.resolve(FieldKeyFile)] = fileVal
 		}
 	}
diff --git a/text_formatter.go b/text_formatter.go
index e01587c..5460200 100644
--- a/text_formatter.go
+++ b/text_formatter.go
@@ -139,7 +139,7 @@ func (f *TextFormatter) Format(entry *Entry) ([]byte, error) {
 		if funcVal != "" {
 			fixedKeys = append(fixedKeys, f.FieldMap.resolve(FieldKeyFunc))
 		}
-		if fileVal != "" {
+		if fileVal != ":0" {
 			fixedKeys = append(fixedKeys, f.FieldMap.resolve(FieldKeyFile))
 		}
 	}