diff --git a/MagickCore/stream.c b/MagickCore/stream.c
index 5bd9832..d52ef98 100644
--- a/MagickCore/stream.c
+++ b/MagickCore/stream.c
@@ -908,7 +908,7 @@
   cache_info->rows=rows;
   number_pixels=(MagickSizeType) columns*rows;
   length=(size_t) number_pixels*cache_info->number_channels*sizeof(Quantum);
-  if (length == 0)
+  if (cache_info->number_channels == 0)
     length=number_pixels*sizeof(Quantum);
   if (cache_info->metacontent_extent != 0)
     length+=number_pixels*cache_info->metacontent_extent;