diff --git a/client.cpp b/client.cpp
index ea1322302b..aced224a4b 100644
--- a/client.cpp
+++ b/client.cpp
@@ -1362,7 +1362,7 @@ void Client::updateHiddenPreview()
     }
 }
 
-void Client::sendClientMessage(xcb_window_t w, xcb_atom_t a, xcb_atom_t protocol, long data1, long data2, long data3)
+void Client::sendClientMessage(xcb_window_t w, xcb_atom_t a, xcb_atom_t protocol, uint32_t data1, uint32_t data2, uint32_t data3)
 {
     xcb_client_message_event_t ev;
     memset(&ev, 0, sizeof(ev));
diff --git a/client.h b/client.h
index 2f4f714c77..b7b537d112 100644
--- a/client.h
+++ b/client.h
@@ -824,7 +824,7 @@ private:
     void killProcess(bool ask, xcb_timestamp_t timestamp = XCB_TIME_CURRENT_TIME);
     void updateUrgency();
     static void sendClientMessage(xcb_window_t w, xcb_atom_t a, xcb_atom_t protocol,
-                                  long data1 = 0, long data2 = 0, long data3 = 0);
+                                  uint32_t data1 = 0, uint32_t data2 = 0, uint32_t data3 = 0);
 
     void embedClient(xcb_window_t w, xcb_visualid_t visualid, xcb_colormap_t colormap, uint8_t depth);
     void detectNoBorder();