diff --git a/Command/Log.hs b/Command/Log.hs
index 78190f28fb..3eba85040d 100644
--- a/Command/Log.hs
+++ b/Command/Log.hs
@@ -80,8 +80,8 @@ optParser desc = LogOptions
 		<> help "display history of total sizes of all repositories"
 		)
 	<*> optional (option (eitherReader parseDuration)
-		( long "when" <> metavar paramTime
-		<> help "when to display changed size"
+		( long "interval" <> metavar paramTime
+		<> help "minimum time between displays of changed size"
 		))
 	<*> switch
 		( long "raw-date"
diff --git a/doc/git-annex-log.mdwn b/doc/git-annex-log.mdwn
index 5db94468fb..65636e5c9c 100644
--- a/doc/git-annex-log.mdwn
+++ b/doc/git-annex-log.mdwn
@@ -61,11 +61,11 @@ false, information may not have been committed to the branch yet.
   This is like `--sizesof`, but it displays the total size of all
   known repositories.
 
-* `--when=time`
+* `--interval=time`
 
   When using `--sizesof`, `--sizes`, and `--totalsizes`, this 
-  controls how often to display the size. The default is to
-  display each change to the size.
+  controls the minimum interval between displays of the size.
+  The default is to display each recorded change to the size.
 
   The time is of the form "30d" or "1y".