Added missing SDL_assert.h
diff --git a/src/render/SDL_render.c b/src/render/SDL_render.c
index 680b324..1b9bfd6 100644
--- a/src/render/SDL_render.c
+++ b/src/render/SDL_render.c
@@ -22,6 +22,7 @@
/* The SDL 2D rendering system */
+#include "SDL_assert.h"
#include "SDL_hints.h"
#include "SDL_log.h"
#include "SDL_render.h"