diff --git a/coders/mask.c b/coders/mask.c
index 41cd0dd..1b317f5 100644
--- a/coders/mask.c
+++ b/coders/mask.c
@@ -102,12 +102,12 @@
     Initialize Image structure.
   */
   assert(image_info != (const ImageInfo *) NULL);
-  assert(image_info->signature == MagickSignature);
+  assert(image_info->signature == MagickCoreSignature);
   if (image_info->debug != MagickFalse)
     (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",
       image_info->filename);
   assert(exception != (ExceptionInfo *) NULL);
-  assert(exception->signature == MagickSignature);
+  assert(exception->signature == MagickCoreSignature);
   read_info=CloneImageInfo(image_info);
   SetImageInfoBlob(read_info,(void *) NULL,0);
   (void) CopyMagickString(read_info->magick,"MIFF",MagickPathExtent);