diff --git a/ui.cpp b/ui.cpp
index 3ecd6d1..a796461 100644
--- a/ui.cpp
+++ b/ui.cpp
@@ -30,6 +30,7 @@
 #include <time.h>
 #include <unistd.h>
 
+#include <functional>
 #include <string>
 
 #include <android-base/file.h>