diff --git a/src/core/cgroup.c b/src/core/cgroup.c
index 98672c26e2..abc30e3990 100644
--- a/src/core/cgroup.c
+++ b/src/core/cgroup.c
@@ -2291,7 +2291,8 @@ int unit_attach_pids_to_cgroup(Unit *u, Set *pids, const char *suffix_path) {
                                 ret = r; /* Remember first error */
 
                         continue;
-                }
+                } else if (ret >= 0)
+                        ret++; /* Count successful additions */
 
                 r = cg_all_unified();
                 if (r < 0)
diff --git a/src/core/scope.c b/src/core/scope.c
index 74f16233c5..63d3288caf 100644
--- a/src/core/scope.c
+++ b/src/core/scope.c
@@ -391,6 +391,12 @@ static int scope_start(Unit *u) {
                 scope_enter_dead(s, SCOPE_FAILURE_RESOURCES);
                 return r;
         }
+        if (r == 0) {
+                log_unit_warning(u, "No PIDs left to attach to the scope's control group, refusing: %m");
+                scope_enter_dead(s, SCOPE_FAILURE_RESOURCES);
+                return -ECHILD;
+        }
+        log_unit_debug(u, "%i %s added to scope's control group.", r, r == 1 ? "process" : "processes");
 
         s->result = SCOPE_SUCCESS;