diff --git a/man7/pthreads.7 b/man7/pthreads.7
index 05f7a7bbe..6b2d62062 100644
--- a/man7/pthreads.7
+++ b/man7/pthreads.7
@@ -107,6 +107,10 @@ CPU affinity
 .RB ( sched_setaffinity (2))
 .SS Pthreads function return values
 Most pthreads functions return 0 on success, and an error number on failure.
+The error numbers that can be returned have the same meaning as
+the error numbers returned in
+.I errno
+by conventional system calls and C library functions.
 Note that the pthreads functions do not set
 .IR errno .
 For each of the pthreads functions that can return an error,