diff --git a/src/core/execute.c b/src/core/execute.c
index 864e3d4921..41b3b3f2b5 100644
--- a/src/core/execute.c
+++ b/src/core/execute.c
@@ -374,7 +374,8 @@ int exec_spawn(Unit *unit,
         assert(command);
         assert(context);
         assert(params);
-        assert(params->fds || (params->n_socket_fds + params->n_storage_fds <= 0));
+        assert(!params->fds || FLAGS_SET(params->flags, EXEC_PASS_FDS));
+        assert(params->fds || (params->n_socket_fds + params->n_storage_fds == 0));
         assert(!params->files_env); /* We fill this field, ensure it comes NULL-initialized to us */
         assert(ret);
 
diff --git a/src/core/service.c b/src/core/service.c
index ba71f97474..be38ec73d8 100644
--- a/src/core/service.c
+++ b/src/core/service.c
@@ -1681,6 +1681,8 @@ static int service_spawn_internal(
 
                 exec_params.open_files = s->open_files;
 
+                exec_params.flags |= EXEC_PASS_FDS;
+
                 log_unit_debug(UNIT(s), "Passing %zu fds to service", exec_params.n_socket_fds + exec_params.n_storage_fds);
         }