diff --git a/example/ex4/AppState.cpp b/example/ex4/AppState.cpp
index 6bd484c7..1d145667 100644
--- a/example/ex4/AppState.cpp
+++ b/example/ex4/AppState.cpp
@@ -98,7 +98,7 @@ void
 AppState::generate_random_mutation() {
     if (rng_() % 1000 > (5 * 1000) / 7) {
         /* p=16% integer */
-        gc_root_v_[next_root_++] = Integer::make(next_int_);
+        gc_root_v_[next_root_++] = Integer::make(gc_.get(), next_int_);
     } else if (rng_() % 1000 > (3 * 1000) / 7) {
         /* p=16% cons */
         gp<Object> random_car = gc_root_v_.at(rng_() % gc_root_v_.size());
diff --git a/src/imgui/VulkanApp.cpp b/src/imgui/VulkanApp.cpp
index b298da86..0d72c365 100644
--- a/src/imgui/VulkanApp.cpp
+++ b/src/imgui/VulkanApp.cpp
@@ -691,9 +691,9 @@ VulkanApp::wait_not_minimized()
 {
     int width = 0;
     int height = 0;
-    SDL_GetWindowSize(window_, &width, &height);
+    SDL_Vulkan_GetDrawableSize(window_, &width, &height);
     while (width == 0 || height == 0) {
-        SDL_GetWindowSize(window_, &width, &height);
+        SDL_Vulkan_GetDrawableSize(window_, &width, &height);
         SDL_WaitEvent(nullptr);
     }
 }