diff --git a/src/PropertyDefinitions.cpp b/src/PropertyDefinitions.cpp
index 393c93f..fc2f3c6 100644
--- a/src/PropertyDefinitions.cpp
+++ b/src/PropertyDefinitions.cpp
@@ -3,6 +3,7 @@
 //
 
 #include "./Properties.h"
+#include <cassert>
 
 using namespace ts;