diff --git a/src/xrt/targets/sdl_test/sdl_device.c b/src/xrt/targets/sdl_test/sdl_device.c
index c1a6fee2b..6a248eba9 100644
--- a/src/xrt/targets/sdl_test/sdl_device.c
+++ b/src/xrt/targets/sdl_test/sdl_device.c
@@ -8,6 +8,8 @@
 
 #include "sdl_internal.h"
 
+#include "math/m_mathinclude.h"
+
 #include "util/u_device.h"
 #include "util/u_distortion_mesh.h"