diff --git a/lib/fastimage.rb b/lib/fastimage.rb
index 3bfceab..d62d858 100644
--- a/lib/fastimage.rb
+++ b/lib/fastimage.rb
@@ -585,7 +585,7 @@ class FastImage
 
       # fields (1) + bg color (1) + pixel ratio (1)
       fields = @stream.read(3).unpack("CCC")[0]
-      if fields & 0x80 # Global Color Table
+      if fields & 0x80 != 0 # Global Color Table
         # 2 * (depth + 1) colors, each occupying 3 bytes (RGB)
         @stream.skip(3 * 2 ** ((fields & 0x7) + 1))
       end
diff --git a/test/fixtures/animated_without_gct.gif b/test/fixtures/animated_without_gct.gif
new file mode 100644
index 0000000..acb4c2d
Binary files /dev/null and b/test/fixtures/animated_without_gct.gif differ
diff --git a/test/test.rb b/test/test.rb
index 3d3f9d3..894fda2 100644
--- a/test/test.rb
+++ b/test/test.rb
@@ -15,6 +15,7 @@ GoodFixtures = {
   "test_v5header.bmp"=>[:bmp, [40, 27]],
   "test.gif"=>[:gif, [17, 32]],
   "animated.gif"=>[:gif, [400, 400]],
+  "animated_without_gct.gif"=>[:gif, [859, 478]],
   "test.jpg"=>[:jpeg, [882, 470]],
   "test.png"=>[:png, [30, 20]],
   "test2.jpg"=>[:jpeg, [250, 188]],
@@ -108,6 +109,7 @@ class FastImageTest < Test::Unit::TestCase
     assert_equal nil, FastImage.animated?(TestUrl + "test.png")
     assert_equal false, FastImage.animated?(TestUrl + "test.gif")
     assert_equal true, FastImage.animated?(TestUrl + "animated.gif")
+    assert_equal true, FastImage.animated?(TestUrl + "animated_without_gct.gif")
   end
 
   def test_should_return_nil_on_fetch_failure