diff --git a/coders/dpx.c b/coders/dpx.c
index 32fb55e..26c32d0 100644
--- a/coders/dpx.c
+++ b/coders/dpx.c
@@ -694,12 +694,12 @@
     Open image file.
   */
   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);
   image=AcquireImage(image_info,exception);
   status=OpenBlob(image_info,image,ReadBinaryBlobMode,exception);
   if (status == MagickFalse)
@@ -1481,9 +1481,9 @@
     Open output image file.
   */
   assert(image_info != (const ImageInfo *) NULL);
-  assert(image_info->signature == MagickSignature);
+  assert(image_info->signature == MagickCoreSignature);
   assert(image != (Image *) NULL);
-  assert(image->signature == MagickSignature);
+  assert(image->signature == MagickCoreSignature);
   if (image->debug != MagickFalse)
     (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
   horizontal_factor=4;
@@ -1511,7 +1511,7 @@
     if ((image->columns % 2) != 0)
       image->columns++;
   assert(exception != (ExceptionInfo *) NULL);
-  assert(exception->signature == MagickSignature);
+  assert(exception->signature == MagickCoreSignature);
   status=OpenBlob(image_info,image,WriteBinaryBlobMode,exception);
   if (status == MagickFalse)
     return(status);