Document RAND library.
diff --git a/doc/crypto/RSA_generate_key.pod b/doc/crypto/RSA_generate_key.pod
index cdf5270..3cdc07f 100644
--- a/doc/crypto/RSA_generate_key.pod
+++ b/doc/crypto/RSA_generate_key.pod
@@ -46,7 +46,7 @@
 
 The process is then repeated for prime q with B<callback(3, 1, cb_arg)>.
 
-=head1 RETURN VALUES
+=head1 RETURN VALUE
 
 If key generation fails, RSA_generate_key() returns B<NULL>; the
 error codes can be obtained by ERR_get_error(3).