diff --git a/doc/crypto/ERR_load_strings.pod b/doc/crypto/ERR_load_strings.pod
index 8071d96eff2695d49b361a82fdedc7b418240c07..86ee5fda24a6ee61936e770d32ec916964e94ba4 100644
--- a/doc/crypto/ERR_load_strings.pod
+++ b/doc/crypto/ERR_load_strings.pod
@@ -39,7 +39,8 @@ to user libraries at runtime.
 =head1 RETURN VALUE
 
 ERR_load_strings() returns no value. ERR_PACK() return the error code.
-ERR_get_next_error_library() returns a new library number.
+ERR_get_next_error_library() returns zero on failure, otherwise a new
+library number.
 
 =head1 SEE ALSO