diff --git a/ll.c b/ll.c
index 4b89061..fd328fa 100644
--- a/ll.c
+++ b/ll.c
@@ -410,7 +410,12 @@ void sqfs_ll_op_getxattr(fuse_req_t req, fuse_ino_t ino,
 }
 
 void sqfs_ll_op_forget(fuse_req_t req, fuse_ino_t ino,
-		unsigned long nlookup) {
+#ifdef HAVE_FUSE_LL_FORGET_OP_64T
+		uint64_t nlookup
+#else
+		unsigned long nlookup
+#endif
+		) {
 	sqfs_ll_i lli;
 	update_access_time();
 	sqfs_ll_iget(req, &lli, SQFS_FUSE_INODE_NONE);
diff --git a/ll.h b/ll.h
index f8721a2..a5550b6 100644
--- a/ll.h
+++ b/ll.h
@@ -109,7 +109,12 @@ void sqfs_ll_op_getxattr(fuse_req_t req, fuse_ino_t ino,
 		);
 
 void sqfs_ll_op_forget(fuse_req_t req, fuse_ino_t ino,
-		unsigned long nlookup);
+#ifdef HAVE_FUSE_LL_FORGET_OP_64T
+		uint64_t nlookup
+#else
+		unsigned long nlookup
+#endif
+		);
 
 void sqfs_ll_op_init(void *userdata, struct fuse_conn_info *conn);
 
diff --git a/m4/squashfuse_fuse.m4 b/m4/squashfuse_fuse.m4
index bf85c92..3773df5 100644
--- a/m4/squashfuse_fuse.m4
+++ b/m4/squashfuse_fuse.m4
@@ -272,6 +272,25 @@ AC_DEFUN([SQ_FUSE_API_VERSION],[
 					[Define if we have two-argument fuse_unmount])
 		])
 
+		AC_CACHE_CHECK([for 64_t third argument to fuse ll forget op],
+				[sq_cv_decl_fuse_forget_64_t],[
+			AC_LINK_IFELSE(
+				[AC_LANG_PROGRAM([
+				#include <fuse.h>
+				#include <fuse_lowlevel.h>],
+					[
+					void f(fuse_req_t, fuse_ino_t, uint64_t);
+					struct fuse_lowlevel_ops flo;
+					flo.forget = f;
+					])],
+				[sq_cv_decl_fuse_forget_64_t=yes],
+				[sq_cv_decl_fuse_forget_64_t=no])
+		])
+		AS_IF([test "x$sq_cv_decl_fuse_forget_64_t" = xyes],[
+			AC_DEFINE([HAVE_FUSE_LL_FORGET_OP_64T],1,
+					[Define if we have uint64_t as type of 3rd arg to ll forget op])
+		])
+
 		AC_CHECK_DECLS([fuse_cmdline_help],,,
 		        [#include <fuse_lowlevel.h>])
 	])