diff --git a/sys/man/3/mouse b/sys/man/3/mouse
index 57772eab9..dbc46cd6b 100644
--- a/sys/man/3/mouse
+++ b/sys/man/3/mouse
@@ -156,15 +156,17 @@ to its default state.
 .TP
 .B blank
 blanks the screen.
-The screen also blanks after 30 minutes of inactivity.
+The screen also blanks after
+.I blanktime
+minutes of inactivity.
 The screen can be unblanked by moving the mouse.
 .TP
 .BI blanktime " minutes"
 sets the timeout before the
-screen blanks; the default is 30 minutes.
+screen blanks.
 If
 .I minutes
-is zero, blanking is disabled.
+is zero, blanking is disabled (this is the default).
 .TP
 .B twitch
 unblanks the screen and resets the idle timeout as if the
diff --git a/sys/src/9/port/devmouse.c b/sys/src/9/port/devmouse.c
index cec16c753..d09d6f7d5 100644
--- a/sys/src/9/port/devmouse.c
+++ b/sys/src/9/port/devmouse.c
@@ -98,7 +98,7 @@ static uchar buttonmap[8] = {
 static int mouseswap;
 static int scrollswap;
 static ulong mousetime;
-static ulong blanktime = 30;	/* in minutes; a half hour */
+static ulong blanktime;
 
 extern Memimage* gscreen;