diff --git a/configure.in b/configure.in
index a572ae7f4..e2dec2539 100644
--- a/configure.in
+++ b/configure.in
@@ -529,7 +529,7 @@ CheckX11()
         AC_PATH_X
         AC_PATH_XTRA
         if test x$have_x = xyes; then
-            CFLAGS="$CFLAGS $X_CFLAGS -DENABLE_X11 -Isrc/video"
+            CFLAGS="$CFLAGS $X_CFLAGS -DENABLE_X11 -Iinclude -Isrc/video"
             if test x$ac_cv_func_shmat != xyes; then
                 CFLAGS="$CFLAGS -DNO_SHARED_MEMORY"
             fi