--- a/src/physfs_archiver_grp.c	Mon Aug 14 01:35:10 2017 -0400
+++ b/src/physfs_archiver_grp.c	Mon Aug 14 02:28:00 2017 -0400
@@ -56,7 +56,8 @@
 } /* grpLoadEntries */
 
 
-static void *GRP_openArchive(PHYSFS_Io *io, const char *name, int forWriting)
+static void *GRP_openArchive(PHYSFS_Io *io, const char *name,
+                             int forWriting, int *claimed)
 {
     PHYSFS_uint8 buf[12];
     PHYSFS_uint32 count = 0;
@@ -70,6 +71,8 @@
     if (memcmp(buf, "KenSilverman", sizeof (buf)) != 0)
         BAIL(PHYSFS_ERR_UNSUPPORTED, NULL);
 
+    *claimed = 1;
+
     BAIL_IF_ERRPASS(!__PHYSFS_readAll(io, &count, sizeof(count)), NULL);
     count = PHYSFS_swapULE32(count);