diff --git a/coders/hrz.c b/coders/hrz.c
index a596898..4cc6ce8 100644
--- a/coders/hrz.c
+++ b/coders/hrz.c
@@ -154,7 +154,7 @@
       ThrowReaderException(CorruptImageError,"UnableToReadImageData");
     p=pixels;
     q=QueueAuthenticPixels(image,0,y,image->columns,1,exception);
-    if (q == (const Quantum *) NULL)
+    if (q == (Quantum *) NULL)
       break;
     for (x=0; x < (ssize_t) image->columns; x++)
     {