diff --git a/backends/graphics/openglsdl/openglsdl-graphics.cpp b/backends/graphics/openglsdl/openglsdl-graphics.cpp
index 3dc643d388d..c6304dcf9cf 100644
--- a/backends/graphics/openglsdl/openglsdl-graphics.cpp
+++ b/backends/graphics/openglsdl/openglsdl-graphics.cpp
@@ -44,6 +44,7 @@ OpenGLSdlGraphicsManager::OpenGLSdlGraphicsManager(SdlEventSource *eventSource,
 	SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 8);
 	SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 8);
 	SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, 8);
+	SDL_GL_SetAttribute(SDL_GL_ALPHA_SIZE, 8);
 	SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 16);
 	SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);