Fixed doxygen warning.
diff --git a/include/SDL_video.h b/include/SDL_video.h
index 6822173..3b02cce 100644
--- a/include/SDL_video.h
+++ b/include/SDL_video.h
@@ -904,6 +904,7 @@ extern DECLSPEC SDL_GLContext SDLCALL SDL_GL_GetCurrentContext(void);
/**
* \brief Get the size of a window's underlying drawable (for use with glViewport).
*
+ * \param window Window from which the drawable size should be queried
* \param w Pointer to variable for storing the width, may be NULL
* \param h Pointer to variable for storing the height, may be NULL
*