diff --git a/internal/captcha/handler.go b/internal/captcha/handler.go
index a0f07f5..011f9b6 100644
--- a/internal/captcha/handler.go
+++ b/internal/captcha/handler.go
@@ -325,12 +325,12 @@ func (h *Handler) Math(imageBase64 string) (result string, err error) {
 		return "", fmt.Errorf("无法识别表达式")
 	}
 
-	result, err = evalMathExpression(expr)
+	evalResult, err := evalMathExpression(expr)
 	if err != nil {
 		return "", err
 	}
 
-	return fmt.Sprintf("%v", result), nil
+	return fmt.Sprintf("%v", evalResult), nil
 }
 
 func preprocessMath(img image.Image) ([]float32, error) {