diff --git a/src/basic/process-util.c b/src/basic/process-util.c
index 53ac2717e3..e3c696a3a6 100644
--- a/src/basic/process-util.c
+++ b/src/basic/process-util.c
@@ -1096,6 +1096,8 @@ int pidref_is_my_child(const PidRef *pid) {
 
         pid_t ppid;
         r = pidref_get_ppid(pid, &ppid);
+        if (r == -EADDRNOTAVAIL) /* if this process is outside of our pidns, it is definitely not our child */
+                return false;
         if (r < 0)
                 return r;