https://github.com/ImageMagick/ImageMagick/issues/194
diff --git a/MagickCore/client.h b/MagickCore/client.h
index beb0d1c..55c8f31 100644
--- a/MagickCore/client.h
+++ b/MagickCore/client.h
@@ -15,8 +15,8 @@
 
   MagickCore client methods.
 */
-#ifndef _MAGICKCORE_CLIENT_H
-#define _MAGICKCORE_CLIENT_H
+#ifndef MAGICKCORE_CLIENT_H
+#define MAGICKCORE_CLIENT_H
 
 #if defined(__cplusplus) || defined(c_plusplus)
 extern "C" {