diff --git a/doc/protocol.rst b/doc/protocol.rst
index 421b3492a..fe60d9c61 100644
--- a/doc/protocol.rst
+++ b/doc/protocol.rst
@@ -464,7 +464,8 @@ Querying :program:`MPD`'s status
     - ``songs``: number of songs
     - ``uptime``: daemon uptime in seconds
     - ``db_playtime``: sum of all song times in the database in seconds
-    - ``db_update``: last db update in UNIX time
+    - ``db_update``: last db update in UNIX time (seconds since
+      1970-01-01 UTC)
     - ``playtime``: time length of music played
 
 Playback options