diff --git a/lib/libpam/openpam_log.c b/lib/libpam/openpam_log.c
index e7d832c..b84a57b 100644
--- a/lib/libpam/openpam_log.c
+++ b/lib/libpam/openpam_log.c
@@ -168,4 +168,6 @@ _openpam_log(int level, const char *func, const char *fmt, ...)
  *
  * The remaining arguments are a =printf format string and the
  * corresponding arguments.
+ *
+ * The =openpam_log function does not modify the value of :errno.
  */