diff --git a/CHANGELOG.md b/CHANGELOG.md
index cee94df..6ac2dec 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,11 @@
 # Changelog #
 
+## Version 10.0.571
+
+- Revert deprecation of `then'` and `chain'`
+- Add **experimental** `promesa.core/wait-all` helper
+
+
 ## Version 10.0.570
 
 - Add `promesa.exec.csp/mult*` alternative multiplexer constructor
diff --git a/README.md b/README.md
index b66702c..d2ea896 100644
--- a/README.md
+++ b/README.md
@@ -18,13 +18,13 @@ Here you can look a detailed [documentation][1].
 deps.edn:
 
 ```clojure
-funcool/promesa {:mvn/version "10.0.570"}
+funcool/promesa {:mvn/version "10.0.571"}
 ```
 
 Leiningen:
 
 ```clojure
-[funcool/promesa "10.0.570"]
+[funcool/promesa "10.0.571"]
 ```
 
 ## On the REPL
diff --git a/src/promesa/core.cljc b/src/promesa/core.cljc
index 790544e..27c4e5d 100644
--- a/src/promesa/core.cljc
+++ b/src/promesa/core.cljc
@@ -147,8 +147,14 @@
    (pt/-bind (pt/-promise p) (comp pt/-promise f) executor)))
 
 (defn then'
-  {:deprecated "9.3"
-   :no-doc true}
+  "Chains a function `f` to be executed when the promise `p` is
+  successfully resolved. Returns a promise that will be resolved with
+  the return value of calling `f` with value as single argument; `f`
+  should return a plain value, no automatic unwrapping will be
+  performed.
+
+  The computation will be executed in the completion thread by
+  default; you also can provide a custom executor."
   ([p f]
    (pt/-map (pt/-promise p) f))
   ([p f executor]
@@ -214,12 +220,13 @@
   "Chain variable number of functions to be executed serially using
   `then`."
   ([p f] (then p f))
-  ([p f & fs] (reduce #(then %1 %2) p (cons f fs))))
+  ([p f & fs] (reduce then p (cons f fs))))
 
 (defn chain'
-  {:deprecated "9.3" :no-doc true}
+  "Chain variable number of functions to be executed serially using
+  `map`."
   ([p f] (then' p f))
-  ([p f & fs] (reduce pt/-map (pt/-promise p) (cons f fs))))
+  ([p f & fs] (reduce #(map %2 %1) (pt/-promise p) (cons f fs))))
 
 (defn handle
   "Chains a function `f` to be executed when the promise `p` is completed
@@ -361,6 +368,23 @@
             (c/->> (CompletableFuture/allOf (into-array CompletableFuture promises))
                    (map (fn [_]
                           (c/mapv pt/-extract promises)))))))
+
+(defn wait-all
+  "Given a variable number of promises, returns a promise which resolves
+  to `nil` when all provided promises complete (rejected or resolved).
+
+  **EXPERIMENTAL**"
+  [& promises]
+  (c/let [state (atom (into #{} promises))
+          d     (deferred)]
+    (c/run! (fn [p]
+              (fnly (fn [_ _]
+                      (when-not (seq (swap! state disj p))
+                        (pt/-resolve! d nil)))
+                    p))
+            promises)
+    d))
+
 (defn race
   [promises]
   #?(:cljs (.race impl/*default-promise* (into-array (c/map pt/-promise promises)))
diff --git a/src/promesa/exec/csp.clj b/src/promesa/exec/csp.clj
index 2fa0c1e..a766660 100644
--- a/src/promesa/exec/csp.clj
+++ b/src/promesa/exec/csp.clj
@@ -382,6 +382,7 @@
                                             (pt/-untap! mx ch)))))))
            (recur))
          (pt/-close! mx)))
+
      mx)))
 
 (defn mult
diff --git a/test/promesa/tests/core_test.cljc b/test/promesa/tests/core_test.cljc
index 9a5dcf6..0a4291a 100644
--- a/test/promesa/tests/core_test.cljc
+++ b/test/promesa/tests/core_test.cljc
@@ -90,14 +90,14 @@
 (t/deftest promise-from-nil-value
   #?(:cljs
      (t/async done
-       (p/then (p/promise nil)
-               (fn [v]
-                 (t/is (= v nil))
-                 (done))))
+       (p/then' (p/promise nil)
+                (fn [v]
+                  (t/is (= v nil))
+                  (done))))
      :clj
-     @(p/then (p/promise nil)
-              (fn [v]
-                (t/is (= v nil))))))
+     @(p/then' (p/promise nil)
+               (fn [v]
+                 (t/is (= v nil))))))
 
 
 (t/deftest promise-from-factory
@@ -442,6 +442,19 @@
            p2 (p/chain p1 inc inc inc)]
        (t/is (= @p2 5)))))
 
+(t/deftest chaining-using-chain'
+  #?(:cljs
+     (t/async done
+       (let [p1 (promise-ok 100 2)
+             p2 (p/chain' p1 inc inc inc)]
+         (p/then p2 (fn [v]
+                      (t/is (= v 5))
+                      (done)))))
+     :clj
+     (let [p1 (promise-ok 100 2)
+           p2 (p/chain' p1 inc inc inc)]
+       (t/is (= @p2 5)))))
+
 (t/deftest promisify
   #?(:cljs
      (t/async done