diff --git a/CompareFS/PathComparator.cs b/CompareFS/PathComparator.cs
index 50607a7..52638c8 100644
--- a/CompareFS/PathComparator.cs
+++ b/CompareFS/PathComparator.cs
@@ -10,9 +10,13 @@ public class PathComparator
     {
         private IPathModificationListener Listener;
 
+        public List<string> ExcludedFileExtensions { get; private set; }
+
         public PathComparator(IPathModificationListener listener)
         {
             Listener = listener;
+
+            ExcludedFileExtensions = new List<string>();
         }
 
         public void Compare(DirectoryInfo referenceDirectory, DirectoryInfo targetDirectory)
@@ -40,14 +44,19 @@ private void CompareSubdirectories(DirectoryInfo referenceDirectory, DirectoryIn
 
         private void CompareFiles(DirectoryInfo referenceDirectory, DirectoryInfo targetDirectory)
         {
-            foreach (FileInfo fi in targetDirectory.EnumerateFiles().Where(f => !referenceDirectory.HasFile(f)))
+            foreach (FileInfo fi in EnumerateLeftFilesMissingRight(targetDirectory, referenceDirectory))
             {
                 Listener.OnModification(new FileModification(fi, ModificationType.Added));
             }
-            foreach (FileInfo fi in referenceDirectory.EnumerateFiles().Where(f => !targetDirectory.HasFile(f)))
+            foreach (FileInfo fi in EnumerateLeftFilesMissingRight(referenceDirectory, targetDirectory))
             {
                 Listener.OnModification(new FileModification(fi, ModificationType.Removed));
             }
         }
+
+        private IEnumerable<FileInfo> EnumerateLeftFilesMissingRight(DirectoryInfo leftFiles, DirectoryInfo rightFiles)
+        {
+            return leftFiles.EnumerateFiles().Where(f => !ExcludedFileExtensions.Contains(f.Extension)).Where(f => !rightFiles.HasFile(f));
+        }
     }
 }
diff --git a/ComparePathCLI/Program.cs b/ComparePathCLI/Program.cs
index efaa31f..98b4942 100644
--- a/ComparePathCLI/Program.cs
+++ b/ComparePathCLI/Program.cs
@@ -11,14 +11,27 @@ class Program
     {
         static void Main(string[] args)
         {
-            if (args.Length < 2)
+            if (args.Length < 2 || args.Length % 2 != 0)
             {
-                Console.WriteLine("Usage: ComparePathCLI path1 path2");
+                Console.WriteLine("Usage: ComparePathCLI (-i extension)* path1 path2");
                 return;
             }
 
             var comparator = new PathComparator(new PathModificationConsoleWriter());
-            comparator.Compare(new DirectoryInfo(args[0]), new DirectoryInfo(args[1]));
+
+            for (int i = 0; i < args.Length - 2; i += 2)
+            {
+                if (args[i] == "-i")
+                {
+                    comparator.ExcludedFileExtensions.Add(args[i+1]);
+                }
+                else
+                {
+                    Console.WriteLine("Skipping unknown option \"{0}\"", args[i]);
+                }
+            }
+
+            comparator.Compare(new DirectoryInfo(args[args.Length - 2]), new DirectoryInfo(args[args.Length - 1]));
         }
     }
 }