diff --git a/autotests/client/test_error.cpp b/autotests/client/test_error.cpp
--- a/autotests/client/test_error.cpp
+++ b/autotests/client/test_error.cpp
@@ -35,6 +35,8 @@
 
 #include <wayland-client-protocol.h>
 
+#include <errno.h>  // For EPROTO
+
 using namespace KWayland::Client;
 using namespace KWayland::Server;