diff --git a/include/lldb/Utility/TaskPool.h b/include/lldb/Utility/TaskPool.h
index db15b2081..3e6d5df8f 100644
--- a/include/lldb/Utility/TaskPool.h
+++ b/include/lldb/Utility/TaskPool.h
@@ -33,6 +33,7 @@
 #include <queue>
 #include <thread>
 #include <vector>
+#include <functional>
 
 // Global TaskPool class for running tasks in parallel on a set of worker thread
 // created the first