diff --git a/src/event.c b/src/event.c
index 07c2a21..46340d6 100644
--- a/src/event.c
+++ b/src/event.c
@@ -349,15 +349,13 @@ static inline void ev_reparent_notify(session_t *ps, xcb_reparent_notify_event_t
 		    ps->c, ev->window, XCB_CW_EVENT_MASK,
 		    (const uint32_t[]){determine_evmask(ps, ev->window, WIN_EVMODE_UNKNOWN)});
 
-		// Check if the window is an undetected client window
-		// Firstly, check if it's a known client window
-		if (!w_top) {
-			// If not, look for its frame window
-			auto w_real_top = find_managed_window_or_parent(ps, ev->parent);
-			// If found, and the client window has not been determined, or its
-			// frame may not have a correct client, continue
-			if (w_real_top && (!w_real_top->client_win ||
-			                   w_real_top->client_win == w_real_top->base.id)) {
+		// Mark the window as the client window of its parent.
+		auto w_real_top = find_managed_window_or_parent(ps, ev->parent);
+		// If found, and the client window has not been determined, or its
+		// frame may not have a correct client, continue
+		if (w_real_top) {
+			if (!w_real_top->client_win ||
+			    w_real_top->client_win == w_real_top->base.id) {
 				// If it has WM_STATE, mark it the client window
 				if (wid_has_prop(ps, ev->window, ps->atoms->aWM_STATE)) {
 					w_real_top->wmwin = false;
@@ -372,6 +370,11 @@ static inline void ev_reparent_notify(session_t *ps, xcb_reparent_notify_event_t
 					        determine_evmask(ps, ev->window, WIN_EVMODE_UNKNOWN) |
 					        XCB_EVENT_MASK_PROPERTY_CHANGE});
 				}
+			} else {
+				log_warn("Window %#010x reparented to a window that "
+				         "already has a client window, the parent is "
+				         "%#010x (%s)",
+				         ev->window, w_real_top->base.id, w_real_top->name);
 			}
 		}
 	}