Index: sys/compat/linux/linux_misc.c
===================================================================
--- sys/compat/linux/linux_misc.c
+++ sys/compat/linux/linux_misc.c
@@ -1055,7 +1055,7 @@
 int
 linux_wait4(struct thread *td, struct linux_wait4_args *args)
 {
-	int options, id, idtype;
+	int error, options, id, idtype;
 
 	if (args->options & ~(LINUX_WUNTRACED | LINUX_WNOHANG |
 	    LINUX_WCONTINUED | __WCLONE | __WNOTHREAD | __WALL))
@@ -1077,6 +1077,11 @@
 	} else if (args->pid < 0) {
 		idtype = P_PGID;
 		id = (id_t)-args->pid;
+	} else if (args->pid == 0) {
+		idtype = P_PGID;
+		error = kern_getpgid(td, args->pid, &id);
+		if (error != 0)
+			return (error);
 	} else {
 		idtype = P_PID;
 		id = (id_t)args->pid;