diff --git a/libarchive/archive_read_disk_entry_from_file.c b/libarchive/archive_read_disk_entry_from_file.c
index b2f1d17..4e1de0e 100644
--- a/libarchive/archive_read_disk_entry_from_file.c
+++ b/libarchive/archive_read_disk_entry_from_file.c
@@ -674,7 +674,9 @@
 	{ARCHIVE_ENTRY_ACL_READ_ACL, ACL_READ_SECURITY},
 	{ARCHIVE_ENTRY_ACL_WRITE_ACL, ACL_WRITE_SECURITY},
 	{ARCHIVE_ENTRY_ACL_WRITE_OWNER, ACL_CHANGE_OWNER},
+#ifdef ACL_SYNCHRONIZE
 	{ARCHIVE_ENTRY_ACL_SYNCHRONIZE, ACL_SYNCHRONIZE}
+#endif
 #else	/* POSIX.1e ACL permissions */
 	{ARCHIVE_ENTRY_ACL_EXECUTE, ACL_EXECUTE},
 	{ARCHIVE_ENTRY_ACL_WRITE, ACL_WRITE},
@@ -1382,6 +1384,11 @@
 				ae_perm |= acl_perm_map[i].archive_perm;
 		}
 
+#if defined(HAVE_DARWIN_ACL) && !defined(ACL_SYNCHRONIZE)
+		/* On Mac OS X without ACL_SYNCHRONIZE assume it is set */
+		ae_perm |= ARCHIVE_ENTRY_ACL_SYNCHRONIZE;
+#endif
+
 		archive_entry_acl_add_entry(entry, entry_acl_type,
 					    ae_perm, ae_tag,
 					    ae_id, ae_name);
diff --git a/libarchive/archive_write_disk_acl.c b/libarchive/archive_write_disk_acl.c
index 144ab7e..30727fb 100644
--- a/libarchive/archive_write_disk_acl.c
+++ b/libarchive/archive_write_disk_acl.c
@@ -158,7 +158,9 @@
 	{ARCHIVE_ENTRY_ACL_READ_ACL, ACL_READ_SECURITY},
 	{ARCHIVE_ENTRY_ACL_WRITE_ACL, ACL_WRITE_SECURITY},
 	{ARCHIVE_ENTRY_ACL_WRITE_OWNER, ACL_CHANGE_OWNER},
+#ifdef ACL_SYNCHRONIZE
 	{ARCHIVE_ENTRY_ACL_SYNCHRONIZE, ACL_SYNCHRONIZE}
+#endif
 #else	/* POSIX.1e ACL permissions */
 	{ARCHIVE_ENTRY_ACL_EXECUTE, ACL_EXECUTE},
 	{ARCHIVE_ENTRY_ACL_WRITE, ACL_WRITE},