diff -ur src.orig/ArtworkFormat.cs src/ArtworkFormat.cs
--- src.orig/ArtworkFormat.cs	2007-10-09 13:35:38.000000000 -0300
+++ src/ArtworkFormat.cs	2008-12-14 21:37:30.000000000 -0400
@@ -67,5 +67,18 @@
         public short CorrelationId {
             get { return correlationId; }
         }
+
+        public override bool Equals(object right) {
+            ArtworkFormat a = right as ArtworkFormat;
+            return
+                a != null &&
+                a.Usage == this.Usage &&
+                a.Width == this.Width &&
+                a.Height == this.Height &&
+                a.CorrelationId == this.CorrelationId &&
+                a.Size == this.Size &&
+                a.PixelFormat == this.PixelFormat &&
+                a.Rotation == this.Rotation;
+        }
     }
 }
diff -ur src.orig/Photo.cs src/Photo.cs
--- src.orig/Photo.cs	2007-10-10 12:32:12.000000000 -0300
+++ src/Photo.cs	2008-12-14 21:31:00.000000000 -0400
@@ -112,7 +112,7 @@
 
         public Thumbnail LookupThumbnail (ArtworkFormat format) {
             foreach (Thumbnail thumbnail in thumbnails) {
-                if (thumbnail.Format == format) {
+                if (thumbnail.Format.Equals(format)) {
                     return thumbnail;
                 }
             }
