diff --git a/Makefile b/Makefile
index 99fcad1..871dc26 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 SDL_CFLAGS := $(shell sdl2-config --cflags)
 SDL_LFLAGS := -lSDL2_ttf $(shell sdl2-config --libs)
 
-CXXFLAGS = -Isrc -Isrc/sys -D_SYSTEM3 -D_DEBUG_CONSOLE -MMD $(SDL_CFLAGS)
+CXXFLAGS = -Isrc -Isrc/sys -D_SYSTEM3 -D_DEBUG_CONSOLE -MMD $(SDL_CFLAGS) -g
 
 LIBS = -lfreetype -lharfbuzz -lglib-2.0 -lpng -lbz2 -lz -lintl -liconv \
 	-luuid -limm32 -lole32 -loleaut32 -lversion -lgdi32 -lgdiplus -lwinmm -lws2_32
diff --git a/src/sys/ags.cpp b/src/sys/ags.cpp
index 83a128c..bc5b907 100644
--- a/src/sys/ags.cpp
+++ b/src/sys/ags.cpp
@@ -453,6 +453,8 @@ void AGS::invalidate_screen(int sx, int sy, int width, int height)
 {
 	SDL_UnlockSurface(hBmpDest);
 	uint32* pixels = surface_line(hBmpDest, screen_height == 400 ? sy + (scroll - 400) : sy) + sx;
+	if (sy + height > screen_height)
+		height = screen_height - sy;
 	SDL_Rect rect = {sx, sy, width, height};
 	SDL_UpdateTexture(sdlTexture, &rect, pixels, hBmpDest->pitch);
 	SDL_RenderClear(sdlRenderer);