diff --git a/app/src/sys/unix/command.c b/app/src/sys/unix/command.c
index ed9bbeac..9eb537b9 100644
--- a/app/src/sys/unix/command.c
+++ b/app/src/sys/unix/command.c
@@ -1,3 +1,5 @@
+#define _POSIX_SOURCE // for kill()
+
 #include "command.h"
 
 #include <errno.h>