diff --git a/src/uscxml/interpreter/InterpreterMonitor.h b/src/uscxml/interpreter/InterpreterMonitor.h
index 64c281c01..d3b9c6336 100644
--- a/src/uscxml/interpreter/InterpreterMonitor.h
+++ b/src/uscxml/interpreter/InterpreterMonitor.h
@@ -25,6 +25,7 @@
 #include "uscxml/interpreter/Logging.h"
 #include "uscxml/debug/InterpreterIssue.h"
 
+#include <functional>
 #include <mutex>
 
 #define USCXML_MONITOR_CATCH(callback) \