diff --git a/headless/Headless.cpp b/headless/Headless.cpp
index 2b96974088..e33f85ea2f 100644
--- a/headless/Headless.cpp
+++ b/headless/Headless.cpp
@@ -330,12 +330,14 @@ struct AutoTestOptions {
 	int requiredDisableHLE;
 };
 
-// Ends a frame of the draw context the way the app does, presenting it. With Vulkan, presenting is
-// also what returns a frame's image, and a frame that isn't presented would wait forever for its
-// next one. The other backends present to a hidden window, which could wait for vsync.
+// Ends a frame of the draw context the way the app does, presenting it. Unpresented frames never
+// finish: with Vulkan, presenting is what returns a frame's image, and OpenGL's render thread only
+// finishes a frame when it's presented, so either would eventually wait forever. Neither waits for
+// vsync here (Vulkan and, on macOS, OpenGL render offscreen, and the hidden-window OpenGL context
+// swaps with interval 0). D3D11 presents to a hidden window, which could.
 static void EndDrawFrame(Draw::DrawContext *draw) {
 	draw->EndFrame();
-	if (GetGPUBackend() == GPUBackend::VULKAN) {
+	if (GetGPUBackend() == GPUBackend::VULKAN || GetGPUBackend() == GPUBackend::OPENGL) {
 		draw->Present(Draw::PresentMode::FIFO);
 	}
 }