diff --git a/man2/futex.2 b/man2/futex.2
index 5a7aeef08..1c9e98ca4 100644
--- a/man2/futex.2
+++ b/man2/futex.2
@@ -676,11 +676,13 @@ and
 .IR val3
 arguments are ignored.
 .\" FIXME
-.\" > [EOWNERDIED] The owner of the futex died and the kernel made the 
-.\" > caller the new owner. The kernel sets the FUTEX_OWNER_DIED bit in
-.\" > the futex userspace value. Caller is responsible for cleanup
+.\" tglx noted the following "ERROR" case for FUTEX_LOCK_PI and
+.\" FUTEX_TRYLOCK_PI
+.\"     > [EOWNERDIED] The owner of the futex died and the kernel made the 
+.\"     > caller the new owner. The kernel sets the FUTEX_OWNER_DIED bit
+.\"     > in the futex userspace value. Caller is responsible for cleanup
 .\"
-.\" There is no such thing as an EOWNERDIED error. I had a look
+.\" However, there is no such thing as an EOWNERDIED error. I had a look
 .\" through the kernel source for the FUTEX_OWNER_DIED cases and didn't 
 .\" see an obvious error associated with them. Can you clarify? (I think 
 .\" the point is that this condition, which is described in
@@ -895,6 +897,16 @@ but the accompanying operation was neither
 nor
 .BR FUTEX_WAIT_REQUEUE_PI .
 .TP
+.BR ENOSYS
+.RB ( FUTEX_LOCK_PI ,
+.BR FUTEX_TRYLOCK_PI )
+A run-time check determined that the operation not available.
+.BR FUTEX_LOCK_PI
+and
+.BR FUTEX_TRYLOCK_PI
+are not implemented on all architectures and
+not supported on some CPU variants.  
+.TP
 .BR EPERM
 .RB ( FUTEX_LOCK_PI ,
 .BR FUTEX_TRYLOCK_PI )