diff --git a/coders/mpc.c b/coders/mpc.c
index 3c7a13cc48..10d164d39d 100644
--- a/coders/mpc.c
+++ b/coders/mpc.c
@@ -786,7 +786,7 @@ static Image *ReadMPCImage(const ImageInfo *image_info,ExceptionInfo *exception)
         (image->compression == UndefinedCompression) ||
         (image->columns == 0) || (image->rows == 0) ||
         (image->number_channels > MaxPixelChannels) ||
-        (image->number_meta_channels > (MaxPixelChannels-MetaPixelChannels)) ||
+        (image->number_meta_channels > (size_t) (MaxPixelChannels-MetaPixelChannels)) ||
         ((image->number_channels+image->number_meta_channels) >= MaxPixelChannels) ||
         (image->depth == 0) || (image->depth > 64))
       {