diff --git a/man2/mmap.2 b/man2/mmap.2
index 3d3d1882f..7ca39ff5d 100644
--- a/man2/mmap.2
+++ b/man2/mmap.2
@@ -87,6 +87,8 @@ in the file (or other object) referred to by the file descriptor
 .I offset
 must be a multiple of the page size as returned by
 .IR sysconf(_SC_PAGE_SIZE) .
+The file descriptor can be closed immediately without invalidating the
+mapping.
 .PP
 The
 .I prot