diff --git a/ChangeLog.asciidoc b/ChangeLog.asciidoc
index 957375f9d..b9c51fb3e 100644
--- a/ChangeLog.asciidoc
+++ b/ChangeLog.asciidoc
@@ -29,6 +29,7 @@ https://weechat.org/files/releasenotes/ReleaseNotes-devel.html[release notes]
 [[1.5_bugs]]
 === Bugs fixed
 
+* core: fix update of window title under tmux (issue #685)
 * core: fix detection of python shared libraries (issue #676)
 * api: fix number of arguments returned by function string_split() when
   keep_eol is 2 and the string ends with separators
diff --git a/src/gui/curses/gui-curses-window.c b/src/gui/curses/gui-curses-window.c
index 20856b3d9..aa96c397c 100644
--- a/src/gui/curses/gui-curses-window.c
+++ b/src/gui/curses/gui-curses-window.c
@@ -2467,7 +2467,8 @@ gui_window_set_title (const char *title)
     {
         printf ("\33]0;%s\7", new_title);
     }
-    else if (strncmp (envterm, "screen", 6) == 0)
+    else if ((strncmp (envterm, "screen", 6) == 0)
+             || (strncmp (envterm, "tmux", 4) == 0))
     {
         if (title && title[0])
         {