diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3358cf9..759f6ba 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -43,6 +43,7 @@
 
 ### Internal
 
+* Replace the fixed `run-with-timer` delay in `helm-projectile-grep`/`helm-projectile-ack` (used so a search invoked as an action didn't start until the current Helm session tore down) with `helm-run-after-exit` when a session is live, and a direct call otherwise. No more arbitrary 10ms latency on the standalone commands, and the deferral is now explicit.
 * Tidy up top-level dependencies: `require` `grep` from the helpers that actually use `grep-find-ignored-files`/`-directories` (`helm-projectile--ignored-files`/`-directories`) instead of relying on it being pulled in transitively, and drop the unused `helm-locate` and `helm-global-bindings` requires. (No startup-time change - Helm loads all three transitively anyway; this just makes the dependencies honest.)
 * Drive `helm-projectile-toggle`'s command remaps from a single table (`helm-projectile--command-remaps`) instead of two hand-maintained copies of ~20 `define-key` calls.
 * Extract the remote virtual-Dired guard duplicated across the three Dired file actions into a `helm-projectile--with-virtual-dired` macro.
diff --git a/helm-projectile.el b/helm-projectile.el
index dd257e3..ea094ad 100644
--- a/helm-projectile.el
+++ b/helm-projectile.el
@@ -1558,6 +1558,17 @@ This function is obsolete; use `helm-projectile-mode' instead."
   (interactive)
   (helm-projectile-mode -1))
 
+(defun helm-projectile--run-grep-or-ack (&rest args)
+  "Call `helm-projectile-grep-or-ack' with ARGS.
+When invoked from an action of a live Helm session, defer the search
+until that session has exited (via `helm-run-after-exit'), because a new
+Helm session must not start while the current one is tearing down.
+Otherwise run it right away.  This replaces an old `run-with-timer' that
+guessed a fixed 10ms delay for the same purpose."
+  (if helm-alive-p
+      (apply #'helm-run-after-exit #'helm-projectile-grep-or-ack args)
+    (apply #'helm-projectile-grep-or-ack args)))
+
 ;;;###autoload
 (defun helm-projectile-grep (&optional dir files)
   "Helm version of `projectile-grep'.
@@ -1569,8 +1580,7 @@ prefix argument then ask for FILES."
          (include (if (equal current-prefix-arg '(4))
                       (read-string (projectile-prepend-project-name "Grep in: "))
                     files)))
-    (run-with-timer 0.01 nil
-             #'helm-projectile-grep-or-ack project-root nil nil nil include)))
+    (helm-projectile--run-grep-or-ack project-root nil nil nil include)))
 
 (defun helm-projectile--wildcard-to-ack-match (wildcard)
   "Transform WILDCARD into a form expected by \"match:\" filter of \"ack\"."
@@ -1629,8 +1639,7 @@ Use `helm-projectile-rg' or `helm-projectile-ag' instead."
                             (helm-grep-default-command helm-ack-grep-executable))
                         (helm-grep-read-ack-type))
                     types)))
-    (run-with-timer 0.01 nil
-             #'helm-projectile-grep-or-ack project-root t ignored helm-ack-grep-executable include)))
+    (helm-projectile--run-grep-or-ack project-root t ignored helm-ack-grep-executable include)))
 
 (make-obsolete 'helm-projectile-ack
                "use `helm-projectile-rg' or `helm-projectile-ag' instead."
diff --git a/test/helm-projectile-test-helper.el b/test/helm-projectile-test-helper.el
index a6b69fe..3d7b0a2 100644
--- a/test/helm-projectile-test-helper.el
+++ b/test/helm-projectile-test-helper.el
@@ -91,11 +91,12 @@ plain three-slot string so only the ignore globs vary."
 
 (defun helm-projectile-test--ack-args ()
   "Return the args `helm-projectile-ack' would hand to `helm-projectile-grep-or-ack'.
-`run-with-timer' is stubbed to capture them; the returned list is
+The latter is stubbed to capture them (with no live Helm session, the
+call runs straight through); the returned list is
 \(PROJECT-ROOT USE-ACK-P IGNORED ACK-EXECUTABLE INCLUDE)."
-  (let (args)
-    (cl-letf (((symbol-function 'run-with-timer)
-               (lambda (_delay _repeat _fn &rest rest) (setq args rest))))
+  (let (args (helm-alive-p nil))
+    (cl-letf (((symbol-function 'helm-projectile-grep-or-ack)
+               (lambda (&rest rest) (setq args rest))))
       (helm-projectile-ack))
     args))
 
diff --git a/test/helm-projectile-test.el b/test/helm-projectile-test.el
index 5f6933c..8f67e73 100644
--- a/test/helm-projectile-test.el
+++ b/test/helm-projectile-test.el
@@ -406,6 +406,26 @@
     (expect (helm-projectile-test--ag-command "ag" "--foo")
             :to-equal "ag --ignore TAGS --ignore build/ --foo %s %s %s")))
 
+(describe "helm-projectile--run-grep-or-ack"
+  ;; Replaces the old `run-with-timer' hack: run immediately when no Helm
+  ;; session is live, but defer via `helm-run-after-exit' when invoked as an
+  ;; action from one (so a new session doesn't start mid-teardown).
+  (it "runs the search immediately when no Helm session is live"
+    (spy-on 'helm-projectile-grep-or-ack)
+    (spy-on 'helm-run-after-exit)
+    (let ((helm-alive-p nil))
+      (helm-projectile--run-grep-or-ack "/proj/" nil nil nil nil))
+    (expect 'helm-projectile-grep-or-ack :to-have-been-called)
+    (expect 'helm-run-after-exit :not :to-have-been-called))
+
+  (it "defers via helm-run-after-exit when a Helm session is live"
+    (spy-on 'helm-projectile-grep-or-ack)
+    (spy-on 'helm-run-after-exit)
+    (let ((helm-alive-p t))
+      (helm-projectile--run-grep-or-ack "/proj/" nil nil nil nil))
+    (expect 'helm-run-after-exit :to-have-been-called)
+    (expect 'helm-projectile-grep-or-ack :not :to-have-been-called)))
+
 (describe "helm-projectile-ack deprecation"
   ;; ack is superseded by rg/ag and Projectile dropped `projectile-ack';
   ;; the command is kept working but marked obsolete.