diff --git a/MagickCore/image.h b/MagickCore/image.h
index 693dbd1..ae2765c 100644
--- a/MagickCore/image.h
+++ b/MagickCore/image.h
@@ -39,6 +39,8 @@
   DiscreteAlphaChannel,
   DisassociateAlphaChannel,
   ExtractAlphaChannel,
+  OffAlphaChannel,
+  OnAlphaChannel,
   OpaqueAlphaChannel,
   RemoveAlphaChannel,
   SetAlphaChannel,