diff --git a/src/event.cpp b/src/event.cpp
index badd43a..209bac6 100644
--- a/src/event.cpp
+++ b/src/event.cpp
@@ -1,4 +1,5 @@
 #include <sys/eventfd.h>
+#include <unistd.h>
 
 #include <sdbusplus/event.hpp>
 #include <sdbusplus/exception.hpp>