diff --git a/app/src/main/java/hexlet/code/games/Calc.java b/app/src/main/java/hexlet/code/games/Calc.java
index e806cc1..b3b0733 100644
--- a/app/src/main/java/hexlet/code/games/Calc.java
+++ b/app/src/main/java/hexlet/code/games/Calc.java
@@ -26,8 +26,10 @@ public static String calcAction(int num1, int num2, String action) {
             result = num1 + num2;
         } else if (action.equals("*")) {
             result = num1 * num2;
-        } else {
+        } else if (action.equals("-")) {
             result = num1 - num2;
+        } else {
+            return null;
         }
         return String.valueOf(result);
     }