diff --git a/lib/awful/client.lua.in b/lib/awful/client.lua.in
index 6058bcde..c68dd7b7 100644
--- a/lib/awful/client.lua.in
+++ b/lib/awful/client.lua.in
@@ -405,7 +405,7 @@ end
 --- Set the client as slave: put it at the end of other windows.
 -- @param c The window to set as slave.
 function setslave(c)
-    local cls = capi.client.get(screen)
+    local cls = capi.client.get(c.screen)
     for k, v in pairs(cls) do
         c:swap(v)
     end