diff --git a/doc/crypto/threads.pod b/doc/crypto/threads.pod
index 5f351a166a3da399494205929e684a8f1c6a189a..5da056f3f82366182888269b41727088441c24fb 100644
--- a/doc/crypto/threads.pod
+++ b/doc/crypto/threads.pod
@@ -33,7 +33,7 @@ lock. They can be useful for debugging.
 
 id_function(void) is a function that returns a thread ID. It is not
 needed on Windows nor on platforms where getpid() returns a different
-ID for each thread.
+ID for each thread (most notably Linux).
 
 =head1 RETURN VALUES