diff --git a/doc/fixes3-7-0.txt b/doc/fixes3-7-0.txt
index 9007fa369..c648fd898 100644
--- a/doc/fixes3-7-0.txt
+++ b/doc/fixes3-7-0.txt
@@ -2141,6 +2141,9 @@ tty: have <return> dismiss pick-none menus instead of acting like '>' (not
 tty: menu search via ':' would clobber part of the menu with a status line
 	refresh if the menu was tall enough to cover that
 tty: add support for petattr
+tty: if a ^C interrupt occurred while DECgraphics characters were being drawn
+	on the map, the "Really quit?" prompt would be illegible due to being
+	rendered with VT line drawing characters
 Unix: when user name is used as default character name, keep hyphenated value
 	intact instead stripping off dash and whatever follows as if that
 	specified role/race/&c (worked once upon a time; broken since 3.3.0)
diff --git a/win/tty/wintty.c b/win/tty/wintty.c
index a99acdb58..782688392 100644
--- a/win/tty/wintty.c
+++ b/win/tty/wintty.c
@@ -2225,6 +2225,16 @@ tty_putstr(winid window, int attr, const char *str)
         int suppress_history = (attr & ATR_NOHISTORY),
             urgent_message = (attr & ATR_URGENT);
 
+#if defined(ASCIIGRAPH) && !defined(NO_TERMS)
+        /* if ^C occurs, player is prompted with "Really quit?" and that
+           prompt is issued via tty_putstr(WIN_MESSAGE); if ^C happens
+           while writing DECgraphics chars, the prompt text would be
+           rendered as VT line-drawing characters unless we do this */
+        if (GFlag) {
+            graph_off();
+            GFlag = FALSE;
+        }
+#endif
         /* if message is designated 'urgent' don't suppress it if user has
            typed ESC at --More-- prompt when dismissing an earlier message;
            besides turning off WIN_STOP, we need to prevent current message