diff --git a/coders/heic.c b/coders/heic.c
index b49f880d0f..caf528a7f3 100644
--- a/coders/heic.c
+++ b/coders/heic.c
@@ -641,7 +641,7 @@ static Image *ReadHEICImage(const ImageInfo *image_info,
     *image_handle;
 
   unsigned char
-    magic[12];
+    magic[128];
 
   /*
     Open image file.