diff --git a/webrtc/modules/desktop_capture/mac/window_list_utils.cc b/webrtc/modules/desktop_capture/mac/window_list_utils.cc
index 88b8367d05..6fc697bd9b 100644
--- a/webrtc/modules/desktop_capture/mac/window_list_utils.cc
+++ b/webrtc/modules/desktop_capture/mac/window_list_utils.cc
@@ -141,7 +141,7 @@ bool IsWindowFullScreen(
 bool IsWindowMinimized(CFDictionaryRef window) {
   CFBooleanRef on_screen = reinterpret_cast<CFBooleanRef>(
       CFDictionaryGetValue(window, kCGWindowIsOnscreen));
-  return !CFBooleanGetValue(on_screen);
+  return on_screen != NULL && !CFBooleanGetValue(on_screen);
 }
 
 // Returns true if the window is minimized.