diff --git a/viper.go b/viper.go
index 363a6f3..79c334e 100644
--- a/viper.go
+++ b/viper.go
@@ -1378,7 +1378,13 @@ func (v *Viper) writeConfig(filename string, force bool) error {
 	if err != nil {
 		return err
 	}
-	return v.marshalWriter(f, configType)
+	defer f.Close()
+
+	if err := v.marshalWriter(f, configType); err != nil {
+		return err
+	}
+
+	return f.Sync()
 }
 
 // Unmarshal a Reader into a map.