diff --git a/src/common/util.c b/src/common/util.c
index 44cdd64d6b..61d09aa4a8 100644
--- a/src/common/util.c
+++ b/src/common/util.c
@@ -1408,6 +1408,9 @@ format_rfc1123_time(char *buf, time_t t)
 /** Parse the (a subset of) the RFC1123 encoding of some time (in UTC) from
  * <b>buf</b>, and store the result in *<b>t</b>.
  *
+ * Note that we only accept the subset generated by format_rfc1123_time above,
+ * not the full range of formats suggested by RFC 1123.
+ *
  * Return 0 on success, -1 on failure.
 */
 int