diff --git a/backends/graphics/surfacesdl/surfacesdl-graphics.cpp b/backends/graphics/surfacesdl/surfacesdl-graphics.cpp
index f8e5e2c7535..2c49108c6b8 100644
--- a/backends/graphics/surfacesdl/surfacesdl-graphics.cpp
+++ b/backends/graphics/surfacesdl/surfacesdl-graphics.cpp
@@ -707,12 +707,42 @@ int SurfaceSdlGraphicsManager::getStretchMode() const {
 }
 #endif
 
+void SurfaceSdlGraphicsManager::getDefaultResolution(uint &w, uint &h) {
+#ifdef RS90
+	SDL_PixelFormat p;
+	p.BitsPerPixel = 16;
+	p.BytesPerPixel = 2;
+	p.Rloss = 3;
+	p.Gloss = 2;
+	p.Bloss = 3;
+	p.Rshift = 11;
+	p.Gshift = 5;
+	p.Bshift = 0;
+	p.Rmask = 0xf800;
+	p.Gmask = 0x07e0;
+	p.Bmask = 0x001f;
+	p.colorkey = 0;
+	p.alpha = 0;
+	// Only native screen resolution is supported in RGB565 fullscreen hwsurface.
+	SDL_Rect const* const*availableModes = SDL_ListModes(&p, SDL_FULLSCREEN|SDL_HWSURFACE);
+	w = availableModes[0]->w;
+	h = availableModes[0]->h;
+#else
+	w = 320;
+	h = 200;
+#endif
+}
+
 void SurfaceSdlGraphicsManager::initSize(uint w, uint h, const Graphics::PixelFormat *format) {
 	assert(_transactionMode == kTransactionActive);
 
 	_gameScreenShakeXOffset = 0;
 	_gameScreenShakeYOffset = 0;
 
+	if (w == 0) {
+		getDefaultResolution(w, h);
+	}
+
 #ifdef USE_RGB_COLOR
 	//avoid redundant format changes
 	Graphics::PixelFormat newFormat;
diff --git a/backends/graphics/surfacesdl/surfacesdl-graphics.h b/backends/graphics/surfacesdl/surfacesdl-graphics.h
index 3b039898358..b09d709836c 100644
--- a/backends/graphics/surfacesdl/surfacesdl-graphics.h
+++ b/backends/graphics/surfacesdl/surfacesdl-graphics.h
@@ -428,6 +428,7 @@ protected:
 
 	bool saveScreenshot(const Common::String &filename) const override;
 	virtual void setGraphicsModeIntern();
+	void getDefaultResolution(uint &w, uint &h);
 
 private:
 	void setFullscreenMode(bool enable);
diff --git a/base/main.cpp b/base/main.cpp
index 19534c84530..e5fc9315541 100644
--- a/base/main.cpp
+++ b/base/main.cpp
@@ -351,7 +351,14 @@ static void setupGraphics(OSystem &system) {
 		system.setScaler(ConfMan.get("scaler").c_str(), ConfMan.getInt("scale_factor"));
 		system.setShader(ConfMan.get("shader"));
 
+#ifdef OPENDINGUX
+		// 0, 0 means "autodetect" but currently only SDL supports
+		// it and really useful only on Opendingux. When more platforms
+		// support it we will switch to it.
+		system.initSize(0, 0);
+#else
 		system.initSize(320, 200);
+#endif
 
 		// Parse graphics configuration, implicit fallback to defaults set with RegisterDefaults()
 		system.setFeatureState(OSystem::kFeatureAspectRatioCorrection, ConfMan.getBool("aspect_ratio"));