diff --git a/backends/graphics/null/null-graphics.h b/backends/graphics/null/null-graphics.h
index ff4f9944455..2c15f569793 100644
--- a/backends/graphics/null/null-graphics.h
+++ b/backends/graphics/null/null-graphics.h
@@ -45,7 +45,7 @@ public:
 	inline Graphics::PixelFormat getScreenFormat() const {
 		return Graphics::PixelFormat::createFormatCLUT8();
 	}
-	inline Common::List<Graphics::PixelFormat> getSupportedFormats() {
+	inline Common::List<Graphics::PixelFormat> getSupportedFormats() const {
 		Common::List<Graphics::PixelFormat> list;
 		list.push_back(Graphics::PixelFormat::createFormatCLUT8());
 		return list;