https://github.com/ImageMagick/ImageMagick/issues/194
diff --git a/MagickCore/channel.h b/MagickCore/channel.h
index 5e38ad5..2fee68b 100644
--- a/MagickCore/channel.h
+++ b/MagickCore/channel.h
@@ -15,8 +15,8 @@
 
   MagickCore image channel methods.
 */
-#ifndef _MAGICKCORE_CHANNEL_H
-#define _MAGICKCORE_CHANNEL_H
+#ifndef MAGICKCORE_CHANNEL_H
+#define MAGICKCORE_CHANNEL_H
 
 #include <MagickCore/image.h>