diff --git a/src/tree.c b/src/tree.c
index f5024a55..411e5251 100644
--- a/src/tree.c
+++ b/src/tree.c
@@ -139,8 +139,11 @@ bool tree_close(Con *con, bool kill_window, bool dont_kill_parent) {
         } else {
             /* un-parent the window */
             xcb_reparent_window(conn, con->window->id, root, 0, 0);
-            /* TODO: client_unmap to set state to withdrawn */
-
+            /* We are no longer handling this window, thus set WM_STATE to
+             * WM_STATE_WITHDRAWN (see ICCCM 4.1.3.1) */
+            long data[] = { XCB_ICCCM_WM_STATE_WITHDRAWN, XCB_NONE };
+            xcb_change_property(conn, XCB_PROP_MODE_REPLACE, con->window->id,
+                                A_WM_STATE, A_WM_STATE, 32, 2, data);
         }
         FREE(con->window->class_class);
         FREE(con->window->class_instance);
diff --git a/testcases/t/63-wm-state.t b/testcases/t/63-wm-state.t
new file mode 100644
index 00000000..7e983289
--- /dev/null
+++ b/testcases/t/63-wm-state.t
@@ -0,0 +1,41 @@
+#!perl
+# vim:ts=4:sw=4:expandtab
+#
+# Tests if WM_STATE is WM_STATE_NORMAL when mapped and WM_STATE_WITHDRAWN when
+# unmapped.
+#
+use X11::XCB qw(:all);
+use i3test;
+
+BEGIN {
+    use_ok('X11::XCB::Window');
+    use_ok('X11::XCB::Event::Generic');
+    use_ok('X11::XCB::Event::MapNotify');
+    use_ok('X11::XCB::Event::ClientMessage');
+}
+
+my $x = X11::XCB::Connection->new;
+
+my $window = $x->root->create_child(
+    class => WINDOW_CLASS_INPUT_OUTPUT,
+    rect => [ 0, 0, 30, 30 ],
+    background_color => '#00ff00',
+    event_mask => [ 'structure_notify' ],
+);
+
+$window->name('Window 1');
+$window->map;
+
+diag('window mapped');
+
+sleep 0.5;
+
+is($window->state, ICCCM_WM_STATE_NORMAL, 'WM_STATE normal');
+
+$window->unmap;
+
+sleep 0.5;
+
+is($window->state, ICCCM_WM_STATE_WITHDRAWN, 'WM_STATE withdrawn');
+
+done_testing;