diff --git a/tools/gif2tiff.c b/tools/gif2tiff.c

index 17f7a19..375b152 100644

--- a/tools/gif2tiff.c

+++ b/tools/gif2tiff.c

@@ -333,6 +333,10 @@ readraster(void)

     int status = 1;

     datasize = getc(infile);

+

+    if (datasize > 12)

+        return 0;

+

     clear = 1 << datasize;

     eoi = clear + 1;

     avail = clear + 2;