diff --git a/man2/mprotect.2 b/man2/mprotect.2
index 203aad72a..1daffdd38 100644
--- a/man2/mprotect.2
+++ b/man2/mprotect.2
@@ -109,6 +109,18 @@ or specify one or more pages that are not mapped.
 (Before kernel 2.4.19, the error
 .BR EFAULT
 was incorrectly produced for these cases.)
+.TP
+.B ENOMEM
+Changing the protection of a memory region would result in the total number of
+mappings with distinct attributes (e.g., read versus read/write protection)
+exceeding the allowed maximum.
+.\" I.e., the number of VMAs would exceed the 64kB maximum
+(For example, making the protection of a range
+.BR PROT_READ
+in the middle of a region currently protected as
+.BR PROT_READ|PROT_WRITE
+would result in three mappings:
+two read/write mappings at each end and a read-only mapping in the middle.)
 .SH CONFORMING TO
 SVr4, POSIX.1-2001.
 .\" SVr4 defines an additional error