diff --git a/man2/mprotect.2 b/man2/mprotect.2
index 9bb02eb1b..cbbfd5137 100644
--- a/man2/mprotect.2
+++ b/man2/mprotect.2
@@ -274,7 +274,7 @@ On systems that do not support protection keys in hardware,
 .BR pkey_mprotect ()
 may still be used, but
 .IR pkey
-must be set to 0.
+must be set to -1.
 When called this way, the operation of
 .BR pkey_mprotect ()
 is equivalent to