diff --git a/src/main/java/hu/bme/mit/spaceship/TorpedoStore.java b/src/main/java/hu/bme/mit/spaceship/TorpedoStore.java
index 76a3cea..c7e037f 100644
--- a/src/main/java/hu/bme/mit/spaceship/TorpedoStore.java
+++ b/src/main/java/hu/bme/mit/spaceship/TorpedoStore.java
@@ -8,6 +8,7 @@
 * (Deliberately contains bugs.)
 */
 public class TorpedoStore {
+  Random myrand = new Random();
 
   // rate of failing to fire torpedos [0.0, 1.0]
   private double FAILURE_RATE = 0.0; //NOSONAR
@@ -30,18 +31,18 @@ public TorpedoStore(int numberOfTorpedos){
 
   public boolean fire(int numberOfTorpedos){
     if(numberOfTorpedos < 1 || numberOfTorpedos > this.torpedoCount){
-      new IllegalArgumentException("numberOfTorpedos");
+      throw new IllegalArgumentException("numberOfTorpedos");
     }
 
     boolean success = false;
 
     // simulate random overheating of the launcher bay which prevents firing
-    Random generator = new Random();
-    double r = generator.nextDouble();
+    
+    double r = myrand.nextDouble();
 
     if (r >= FAILURE_RATE) {
       // successful firing
-      this.torpedoCount =- numberOfTorpedos;
+      this.torpedoCount -= numberOfTorpedos;
       success = true;
     } else {
       // simulated failure