diff --git a/NetAF/Interpretation/CustomCommandInterpreter.cs b/NetAF/Interpretation/CustomCommandInterpreter.cs
index 4f79990..f0b6143 100644
--- a/NetAF/Interpretation/CustomCommandInterpreter.cs
+++ b/NetAF/Interpretation/CustomCommandInterpreter.cs
@@ -38,7 +38,7 @@ private static Dictionary<CustomCommand, int> ScoreCommandsAgainstInput(string i
                     if (upperCaseCommand.Length < i + 1 && upperCaseShortcut.Length < i + 1)
                         break;
 
-                    if (upperCaseCommand[i] != upperCaseInput[i] && upperCaseShortcut[i] != upperCaseInput[i])
+                    if (!AreCharactersEqual(upperCaseCommand, upperCaseInput, i) && !AreCharactersEqual(upperCaseShortcut, upperCaseInput, i))
                         break;
                 }
 
@@ -48,6 +48,21 @@ private static Dictionary<CustomCommand, int> ScoreCommandsAgainstInput(string i
             return scores;
         }
 
+        /// <summary>
+        /// Get if a character at a given index is equal in two strings.
+        /// </summary>
+        /// <param name="a">String a.</param>
+        /// <param name="b">String b.</param>
+        /// <param name="index">The index of the character.</param>
+        /// <returns>True if the characters are equal, else false.</returns>
+        private static bool AreCharactersEqual(string a, string b, int index)
+        {
+            if (a.Length - 1 < index || b.Length - 1 < index)
+                return false;
+
+            return a[index] == b[index];
+        }
+
         #endregion
 
         #region Implementation of IInterpreter