diff --git a/src/analyze/analyze-unit-shell.c b/src/analyze/analyze-unit-shell.c
index 576a420034..6d241eb6e1 100644
--- a/src/analyze/analyze-unit-shell.c
+++ b/src/analyze/analyze-unit-shell.c
@@ -2,6 +2,7 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <unistd.h>
 
 #include "sd-bus.h"