diff --git a/modules/event/event_windows.cpp b/modules/event/event_windows.cpp
index ce6027f2..3d413ef3 100644
--- a/modules/event/event_windows.cpp
+++ b/modules/event/event_windows.cpp
@@ -14,6 +14,8 @@
 // Windows Concurrency Runtime's event is not alertible.
 //#include <concrt.h>
 
+#include <cassert>
+
 using namespace std;
 using namespace gsl;