Fixed typo in header comment.
diff --git a/include/SDL_video.h b/include/SDL_video.h
index 49ea37a..607062c 100644
--- a/include/SDL_video.h
+++ b/include/SDL_video.h
@@ -914,7 +914,7 @@ extern DECLSPEC SDL_GLContext SDLCALL SDL_GL_GetCurrentContext(void);
* \param w Pointer to variable for storing the width, may be NULL
* \param h Pointer to variable for storing the height, may be NULL
*
- * This may differ from SDL_GetWindowSize if we're rendering to a high-DPI
+ * This may differ from SDL_GetWindowSize() if we're rendering to a high-DPI
* drawable, i.e. the window was created with SDL_WINDOW_ALLOW_HIGHDPI on a
* platform with high-DPI support (Apple calls this "Retina"), and not disabled
* by the SDL_HINT_VIDEO_HIGHDPI_DISABLED hint.