diff --git a/include/atoms.xmacro b/include/atoms.xmacro
index ac32d8da..41889eb1 100644
--- a/include/atoms.xmacro
+++ b/include/atoms.xmacro
@@ -29,3 +29,5 @@ xmacro(I3_CONFIG_PATH)
 xmacro(I3_SYNC)
 xmacro(I3_SHMLOG_PATH)
 xmacro(I3_PID)
+xmacro(_NET_REQUEST_FRAME_EXTENTS)
+xmacro(_NET_FRAME_EXTENTS)
diff --git a/src/handlers.c b/src/handlers.c
index 6be2a5b1..133d85d0 100644
--- a/src/handlers.c
+++ b/src/handlers.c
@@ -691,6 +691,45 @@ static void handle_client_message(xcb_client_message_event_t *event) {
         xcb_send_event(conn, false, window, XCB_EVENT_MASK_NO_EVENT, (char*)ev);
         xcb_flush(conn);
         free(reply);
+    } else if (event->type == A__NET_REQUEST_FRAME_EXTENTS) {
+        // A client can request an estimate for the frame size which the window
+        // manager will put around it before actually mapping its window. Java
+        // does this (as of openjdk-7).
+        //
+        // Note that the calculation below is not entirely accurate — once you
+        // set a different border type, it’s off. We _could_ request all the
+        // window properties (which have to be set up at this point according
+        // to EWMH), but that seems rather elaborate. The standard explicitly
+        // says the application must cope with an estimate that is not entirely
+        // accurate.
+        DLOG("_NET_REQUEST_FRAME_EXTENTS for window 0x%08x\n", event->window);
+        xcb_get_geometry_reply_t *geometry;
+        xcb_get_geometry_cookie_t cookie = xcb_get_geometry(conn, event->window);
+
+        if (!(geometry = xcb_get_geometry_reply(conn, cookie, NULL))) {
+            ELOG("Could not get geometry of X11 window 0x%08x while handling "
+                 "the _NET_REQUEST_FRAME_EXTENTS ClientMessage\n",
+                 event->window);
+            return;
+        }
+
+        DLOG("Current geometry = x=%d, y=%d, width=%d, height=%d\n",
+             geometry->x, geometry->y, geometry->width, geometry->height);
+
+        Rect r = {
+            0, // left
+            geometry->width + 4, // right
+            0, // top
+            geometry->height + config.font.height + 5, // bottom
+        };
+        xcb_change_property(
+                conn,
+                XCB_PROP_MODE_REPLACE,
+                event->window,
+                A__NET_FRAME_EXTENTS,
+                XCB_ATOM_CARDINAL, 32, 4,
+                &r);
+        xcb_flush(conn);
     } else {
         DLOG("unhandled clientmessage\n");
         return;