diff --git a/cmake/sdlchecks.cmake b/cmake/sdlchecks.cmake
index fd6853f18..7cabbc60c 100644
--- a/cmake/sdlchecks.cmake
+++ b/cmake/sdlchecks.cmake
@@ -312,8 +312,13 @@ macro(CheckX11)
     check_include_file(X11/extensions/scrnsaver.h HAVE_XSS_H)
     check_include_file(X11/extensions/shape.h HAVE_XSHAPE_H)
     check_include_files("X11/Xlib.h;X11/extensions/xf86vmode.h" HAVE_XF86VM_H)
+    check_include_files("X11/Xlib.h;X11/Xproto.h;X11/extensions/Xext.h" HAVE_XEXT_H)
 
     if(X11_LIB)
+      if(NOT HAVE_XEXT_H)
+        message_error("Missing Xext.h, maybe you need to install the libxext-dev package?")
+      endif()
+
       set(HAVE_VIDEO_X11 TRUE)
       set(HAVE_SDL_VIDEO TRUE)