diff --git a/action.lisp b/action.lisp
index 278d1f7634bcb45c67974ecda4bce8b816434c92..6d68ffb7268cc8b99ba7d897e7f090cad9c5abbe 100644
--- a/action.lisp
+++ b/action.lisp
@@ -7,7 +7,6 @@
   (:use :uiop/common-lisp :uiop :asdf/upgrade :asdf/session :asdf/component :asdf/operation)
   (:import-from :asdf/operation #:check-operation-constructor)
   (:import-from :asdf/component #:%additional-input-files)
-  #-clisp (:unintern #:required-components #:traverse-action #:traverse-sub-actions)
   (:export
    #:action #:define-convenience-action-methods
    #:action-description #:format-action
@@ -431,7 +430,8 @@ They may rely on the order of the files to discriminate between inputs.
 
 Updates the action's COMPONENT-OPERATION-TIME to match the COMPUTE-ACTION-STAMP
 using the JUST-DONE flag."))
-  (defgeneric compute-action-stamp (plan operation component &key just-done)
+  (defgeneric compute-action-stamp (plan- operation component &key just-done)
+    ;; NB: using plan- rather than plan above allows clisp to upgrade from 2.26(!)
     (:documentation "Has this action been successfully done already,
 and at what known timestamp has it been done at or will it be done at?
 * PLAN is a plan object modelling future effects of actions,
diff --git a/find-system.lisp b/find-system.lisp
index f5850598a0206c847581ac0ea28f9c28f3151c2d..0a6ae6b516b9a95e373c4332ddd69065c844ba33 100644
--- a/find-system.lisp
+++ b/find-system.lisp
@@ -7,7 +7,6 @@
         :asdf/session :asdf/component :asdf/system :asdf/operation :asdf/action :asdf/lisp-action
         :asdf/find-component :asdf/system-registry :asdf/plan :asdf/operate)
   (:import-from #:asdf/component #:%additional-input-files)
-  #+abcl (:intern #:initialize-source-registry) ;; to upgrade from 3.1.x
   (:export
    #:find-system #:locate-system #:load-asd #:define-op
    #:load-system-definition-error #:error-name #:error-pathname #:error-condition))
diff --git a/lisp-action.lisp b/lisp-action.lisp
index 221907a4b244a3e7773c7e77bbf833ee9e375c60..8bdeb3bfc51c86856d821db639844ee196f34c45 100644
--- a/lisp-action.lisp
+++ b/lisp-action.lisp
@@ -173,7 +173,7 @@ an OPERATION and a COMPONENT."
   (defmethod input-files ((o compile-op) (c system))
     (when (and *warnings-file-type* (not (builtin-system-p c)))
       ;; The most correct way to do it would be to use:
-      ;; (traverse-sub-actions o c :other-systems nil :keep-operation 'compile-op :keep-component 'cl-source-file)
+      ;; (collect-dependencies o c :other-systems nil :keep-operation 'compile-op :keep-component 'cl-source-file)
       ;; but it's expensive and we don't care too much about file order or ASDF extensions.
       (loop :for sub :in (sub-components c :type 'cl-source-file)
             :nconc (remove-if-not 'warnings-file-p (output-files o sub)))))
diff --git a/plan.lisp b/plan.lisp
index 61b3abf0b1a5d55158deaf0da81bd39f20761fbc..3f9bf2b40cab14cf2b67fc2b38f1e9bd8e3fdeec 100644
--- a/plan.lisp
+++ b/plan.lisp
@@ -4,7 +4,7 @@
 (uiop/package:define-package :asdf/plan
   ;; asdf/action below is needed for required-components, traverse-action and traverse-sub-actions
   ;; that used to live there before 3.2.0.
-  (:recycle :asdf/plan :asdf)
+  (:recycle :asdf/plan :asdf/action :asdf)
   (:use :uiop/common-lisp :uiop :asdf/upgrade :asdf/session
         :asdf/component :asdf/operation :asdf/action :asdf/lisp-action
         :asdf/system :asdf/system-registry :asdf/find-component :asdf/forcing)
diff --git a/source-registry.lisp b/source-registry.lisp
index 28ed1feb1e883b3e101de2588fe3008b4d5a81e7..ec3eec371a6fe17fd38e74ddac853e91b0d76b00 100644
--- a/source-registry.lisp
+++ b/source-registry.lisp
@@ -3,9 +3,9 @@
 ;;;; See the Manual and https://bugs.launchpad.net/asdf/+bug/485918
 
 (uiop/package:define-package :asdf/source-registry
-  (:recycle :asdf/source-registry :asdf)
+  ;; NB: asdf/find-system allows upgrade from <=3.2.1 that have initialize-source-registry there
+  (:recycle :asdf/source-registry :asdf/find-system :asdf)
   (:use :uiop/common-lisp :uiop :asdf/upgrade :asdf/system :asdf/system-registry)
-  #+abcl (:import-from :asdf/find-system #:initialize-source-registry) ;; to upgrade from 3.1.x
   (:export
    #:*source-registry-parameter* #:*default-source-registries*
    #:invalid-source-registry