fix SDL_MUSTLOCK

1 files changed, 2 insertions, 2 deletions

diff --git a/tests/hello_world_sdl.cpp b/tests/hello_world_sdl.cpp
index f3fb8ae7..df69b055 100644
--- a/tests/hello_world_sdl.cpp
+++ b/tests/hello_world_sdl.cpp
@@ -8,7 +8,7 @@ int main() {
   SDL_Init(SDL_INIT_VIDEO);
   SDL_Surface *screen = SDL_SetVideoMode(256, 256, 32, SDL_SWSURFACE);
 
-  SDL_LockSurface(screen);
+  if (SDL_MUSTLOCK(screen)) SDL_LockSurface(screen);
   for (int i = 0; i < 256; i++) {
     for (int j = 0; j < 256; j++) {
       *((char*)screen->pixels + i*256*4 + j*4 + 0) = i;
@@ -17,7 +17,7 @@ int main() {
       *((char*)screen->pixels + i*256*4 + j*4 + 3) = 255;
     }
   }
-  SDL_UnlockSurface(screen);
+  if (SDL_MUSTLOCK(screen)) SDL_UnlockSurface(screen);
   SDL_Flip(screen); 
 
   printf("you should see a colored cube.");