diff --git a/valknut/main.cpp b/valknut/main.cpp
index a14009e..f3066b8 100644
--- a/valknut/main.cpp
+++ b/valknut/main.cpp
@@ -23,6 +23,7 @@
 
 #include <stdlib.h>
 #ifndef WIN32
+#include <unistd.h>
 #include <signal.h>
 #endif