diff --git a/src/mount/core.cljc b/src/mount/core.cljc
index 4973067..e3b16cf 100644
--- a/src/mount/core.cljc
+++ b/src/mount/core.cljc
@@ -244,10 +244,14 @@
   (remove (comp :sub? @meta-state) (find-all-states)))
 
 (defn start [& states]
-  (if (-> states first coll?)
-    (apply start (first states))
-    (let [states (or (seq states) (all-without-subs))]
-      {:started (bring states up <)})))
+  (let [fs (-> states first)]
+    (if (coll? fs)
+      (if-not (empty? fs)                ;; (mount/start) vs. (mount/start #{}) vs. (mount/start #{1 2 3})
+        (apply start fs)
+        {:started #{}})
+      (let [states (or (seq states)
+                       (all-without-subs))]
+        {:started (bring states up <)}))))
 
 (defn stop [& states]
   (let [states (or states (find-all-states))
diff --git a/test/core/mount/test/composable_fns.cljc b/test/core/mount/test/composable_fns.cljc
index ab7ff5b..c7ecdb8 100644
--- a/test/core/mount/test/composable_fns.cljc
+++ b/test/core/mount/test/composable_fns.cljc
@@ -154,4 +154,10 @@
         (is (= {:datomic {:uri "datomic:mem://composable-mount"}} (dval config)))
         (is (instance? datomic.peer.LocalConnection (dval conn)))
         (is (vector? (dval nrepl)))
+        (mount/stop)))
+
+    (testing "should not start anything on empty seq of states"
+      (let [scope #{}]
+        (is (= {:started #{}} (-> (only scope)
+                                  mount/start)))
         (mount/stop)))))