diff --git a/lisp/erc/erc.el b/lisp/erc/erc.el
index f01a99a30a2..a2e9e84eef8 100644
--- a/lisp/erc/erc.el
+++ b/lisp/erc/erc.el
@@ -1732,20 +1732,11 @@ FORMS will be evaluated in all buffers having the process PROCESS and
 where PRED matches or in all buffers of the server process if PRED is
 nil."
   (declare (indent 1) (debug (form form body)))
-  ;; Make the evaluation have the correct order
-  (let ((pre (make-symbol "pre"))
-        (pro (make-symbol "pro")))
-    `(let* ((,pro ,process)
-            (,pre ,pred)
-            (res (mapcar (lambda (buffer)
-                           (with-current-buffer buffer
-                             ,@forms))
-                         (erc-buffer-list ,pre
-                                          ,pro))))
-       ;; Silence the byte-compiler by binding the result of mapcar to
-       ;; a variable.
-       (ignore res)
-       res)))
+  (macroexp-let2 nil pred pred
+    `(erc-buffer-filter (lambda ()
+                          (when (or (not ,pred) (funcall ,pred))
+                            ,@forms))
+                        ,process)))
 
 (define-obsolete-function-alias 'erc-iswitchb #'erc-switch-to-buffer "25.1")
 (defun erc--switch-to-buffer (&optional arg)
@@ -2583,9 +2574,8 @@ See also `erc-lurker-trim-nicks'."
 Returns NICK unmodified unless `erc-lurker-trim-nicks' is
 non-nil."
   (if erc-lurker-trim-nicks
-      (replace-regexp-in-string
-       (regexp-opt-charset (string-to-list erc-lurker-ignore-chars))
-       "" nick)
+      (string-trim-right
+       nick (rx-to-string `(+ (in ,@(string-to-list erc-lurker-ignore-chars)))))
     nick))
 
 (defcustom erc-lurker-hide-list nil
diff --git a/test/lisp/erc/erc-tests.el b/test/lisp/erc/erc-tests.el
index 9efcf4a7038..0533d044911 100644
--- a/test/lisp/erc/erc-tests.el
+++ b/test/lisp/erc/erc-tests.el
@@ -24,6 +24,7 @@
 (require 'ert)
 (require 'erc)
 (require 'erc-ring)
+(require 'erc-networks)
 
 (ert-deftest erc--read-time-period ()
   (cl-letf (((symbol-function 'read-string) (lambda (&rest _) "")))
@@ -47,6 +48,85 @@
   (cl-letf (((symbol-function 'read-string) (lambda (&rest _) "1d")))
     (should (equal (erc--read-time-period "foo: ") 86400))))
 
+(ert-deftest erc-with-all-buffers-of-server ()
+  (let (proc-exnet
+        proc-onet
+        erc-kill-channel-hook erc-kill-server-hook erc-kill-buffer-hook)
+
+    (with-current-buffer (get-buffer-create "OtherNet")
+      (erc-mode)
+      (setq proc-onet (start-process "sleep" (current-buffer) "sleep" "1")
+            erc-server-process proc-onet
+            erc-network 'OtherNet)
+      (set-process-query-on-exit-flag erc-server-process nil))
+
+    (with-current-buffer (get-buffer-create "ExampleNet")
+      (erc-mode)
+      (setq proc-exnet (start-process "sleep" (current-buffer) "sleep" "1")
+            erc-server-process proc-exnet
+            erc-network 'ExampleNet)
+      (set-process-query-on-exit-flag erc-server-process nil))
+
+    (with-current-buffer (get-buffer-create "#foo")
+      (erc-mode)
+      (setq erc-server-process proc-exnet)
+      (setq erc-default-recipients '("#foo")))
+
+    (with-current-buffer (get-buffer-create "#spam")
+      (erc-mode)
+      (setq erc-server-process proc-onet)
+      (setq erc-default-recipients '("#spam")))
+
+    (with-current-buffer (get-buffer-create "#bar")
+      (erc-mode)
+      (setq erc-server-process proc-onet)
+      (setq erc-default-recipients '("#bar")))
+
+    (with-current-buffer (get-buffer-create "#baz")
+      (erc-mode)
+      (setq erc-server-process proc-exnet)
+      (setq erc-default-recipients '("#baz")))
+
+    (should (eq (get-buffer-process "ExampleNet") proc-exnet))
+    (erc-with-all-buffers-of-server (get-buffer-process "ExampleNet")
+      nil
+      (kill-buffer))
+
+    (should-not (get-buffer "ExampleNet"))
+    (should-not (get-buffer "#foo"))
+    (should-not (get-buffer "#baz"))
+    (should (get-buffer "OtherNet"))
+    (should (get-buffer "#bar"))
+    (should (get-buffer "#spam"))
+
+    (let* ((test (lambda () (not (string= (buffer-name) "#spam"))))
+           (calls 0)
+           (get-test (lambda () (cl-incf calls) test)))
+
+      (erc-with-all-buffers-of-server proc-onet
+        (funcall get-test)
+        (kill-buffer))
+
+      (should (= calls 1)))
+
+    (should-not (get-buffer "OtherNet"))
+    (should-not (get-buffer "#bar"))
+    (should (get-buffer "#spam"))
+    (kill-buffer "#spam")))
+
+(ert-deftest erc-lurker-maybe-trim ()
+  (let (erc-lurker-trim-nicks
+        (erc-lurker-ignore-chars "_`"))
+
+    (should (string= "nick`" (erc-lurker-maybe-trim "nick`")))
+
+    (setq erc-lurker-trim-nicks t)
+    (should (string= "nick" (erc-lurker-maybe-trim "nick`")))
+    (should (string= "ni`_ck" (erc-lurker-maybe-trim "ni`_ck__``")))
+
+    (setq erc-lurker-ignore-chars "_-`") ; set of chars, not character alts
+    (should (string= "nick" (erc-lurker-maybe-trim "nick-_`")))))
+
 (ert-deftest erc-ring-previous-command-base-case ()
   (ert-info ("Create ring when nonexistent and do nothing")
     (let (erc-input-ring