--- profilea.c	2016-10-11 17:51:01.181070243 +0900
+++ profile.c	2016-10-11 17:53:35.757015859 +0900
@@ -2060,7 +2060,7 @@
       (void) AddValueToSplayTree(exif_resources,q,q);
       tag_value=(ssize_t) ReadProfileShort(endian,q);
       format=(ssize_t) ReadProfileShort(endian,q+2);
-      if ((format-1) >= EXIF_NUM_FORMATS)
+      if ((format < 0) || ((format-1) >= EXIF_NUM_FORMATS))
         break;
       components=(ssize_t) ReadProfileLong(endian,q+4);
       if (components < 0)