diff --git a/SelfPropelledArtilleryUnit/SetArtilleriesGeneric.cs b/SelfPropelledArtilleryUnit/SetArtilleriesGeneric.cs
index 1f60477..eeab600 100644
--- a/SelfPropelledArtilleryUnit/SetArtilleriesGeneric.cs
+++ b/SelfPropelledArtilleryUnit/SetArtilleriesGeneric.cs
@@ -26,7 +26,12 @@ namespace Artilleries
 
         public int Insert(T artillery, int position)
         {
-            if (position < 0 || position > Count || Count == _maxCount)
+            if (Count == _maxCount)
+            {
+                throw new StorageOverflowException(_maxCount);
+            }
+
+            if (position < 0 || position > Count)
             {
                 return -1;
             }
@@ -45,6 +50,11 @@ namespace Artilleries
 
             var result = _places[position];
 
+            if (result == null)
+            {
+                throw new ArtilleryNotFoundException(position);
+            }
+
             _places.RemoveAt(position);
             return result;
         }