diff --git a/src/proc.h b/src/proc.h
index 625e85bbf..aaac1a960 100644
--- a/src/proc.h
+++ b/src/proc.h
@@ -8,6 +8,7 @@
 #include <signal.h>
 #include <stddef.h>
 #include <sys/time.h>  // IWYU pragma: keep
+#include <sys/wait.h>  // IWYU pragma: keep
 #include <unistd.h>
 
 #include <deque>