diff --git a/go-guru.el b/go-guru.el
index c538680d..9a62fb74 100644
--- a/go-guru.el
+++ b/go-guru.el
@@ -1,4 +1,4 @@
-;;; go-guru.el --- Integration of the Go 'guru' analysis tool into Emacs.
+;;; go-guru.el --- Integration of the Go 'guru' analysis tool into Emacs.  -*- lexical-binding: t; -*-
 
 ;; Copyright 2016 The Go Authors. All rights reserved.
 ;; Use of this source code is governed by a BSD-style
@@ -155,7 +155,7 @@ Its value is a comma-separated list of patterns of these forms:
 	golang.org/x/tools/...          # all packages beneath dir
 	...                             # the entire workspace.
 
-A pattern preceded by '-' is negative, so the scope
+A pattern preceded by `-' is negative, so the scope
 	encoding/...,-encoding/xml
 matches all encoding packages except encoding/xml."
   (interactive)
@@ -396,7 +396,7 @@ function containing the current point."
 
 ;;;###autoload
 (defun go-guru-implements ()
-  "Describe the 'implements' relation for types in the package
+  "Describe the `implements' relation for types in the package
 containing the current point."
   (interactive)
   (go-guru--start "implements"))
@@ -425,19 +425,19 @@ identifier."
 ;;;###autoload
 (defun go-guru-whicherrs ()
   "Show globals, constants and types to which the selected
-expression (of type 'error') may refer."
+expression (of type \"error\") may refer."
   (interactive)
   (go-guru--set-scope-if-empty)
   (go-guru--start "whicherrs"))
 
 (defun go-guru-what ()
-  "Run a 'what' query and return the parsed JSON response as an
+  "Run a `what' query and return the parsed JSON response as an
 association list."
   (go-guru--json "what"))
 
 (defun go-guru--hl-symbols (posn face id)
   "Highlight the symbols at the positions POSN by creating
-overlays with face FACE. The attribute 'go-guru-overlay on the
+overlays with face FACE. The attribute `go-guru-overlay' on the
 overlays will be set to ID."
   (save-excursion
     (mapc (lambda (pos)
diff --git a/go-mode.el b/go-mode.el
index 6003f715..c054fe9b 100644
--- a/go-mode.el
+++ b/go-mode.el
@@ -1,4 +1,4 @@
-;;; go-mode.el --- Major mode for the Go programming language
+;;; go-mode.el --- Major mode for the Go programming language   -*- lexical-binding: t; -*-
 
 ;;; Commentary:
 
@@ -147,8 +147,8 @@ constant is changed.")
   :group 'go)
 
 (defcustom go-command "go"
-  "The 'go' command.
-Some users have multiple Go development trees and invoke the 'go'
+  "The `go' command.
+Some users have multiple Go development trees and invoke the `go'
 tool via a wrapper that sets GOROOT and GOPATH based on the
 current directory.  Such users should customize this variable to
 point to the wrapper script."
@@ -156,8 +156,8 @@ point to the wrapper script."
   :group 'go)
 
 (defcustom gofmt-command "gofmt"
-  "The 'gofmt' command.
-Some users may replace this with 'goimports'
+  "The `gofmt' command.
+Some users may replace this with `goimports'
 from https://golang.org/x/tools/cmd/goimports."
   :type 'string
   :group 'go)
@@ -181,7 +181,7 @@ a `before-save-hook'."
   :group 'go)
 
 (defcustom godef-command "godef"
-  "The 'godef' command."
+  "The `godef' command."
   :type 'string
   :group 'go)
 
@@ -197,7 +197,7 @@ a `before-save-hook'."
 This is used in e.g. tab completion in `go-import-add'.
 
 This package provides two functions: `go-packages-go-list' uses
-'go list all' to determine all Go packages. `go-packages-native' uses
+`go list all' to determine all Go packages. `go-packages-native' uses
 elisp to find all .a files in all /pkg/ directories.
 `go-packages-native' is obsolete as it doesn't behave correctly with
 the Go build cache or Go modules."
@@ -289,7 +289,7 @@ Consider using ‘godoc-gogetdoc’ instead for more accurate results."
 (defun godoc-gogetdoc (point)
   "Use the gogetdoc tool to find the documentation for an identifier at POINT.
 
-You can install gogetdoc with 'go get -u github.com/zmb3/gogetdoc'."
+You can install gogetdoc with `go get -u github.com/zmb3/gogetdoc'."
   (if (not (buffer-file-name (go--coverage-origin-buffer)))
       ;; TODO: gogetdoc supports unsaved files, but not introducing
       ;; new artificial files, so this limitation will stay for now.
@@ -735,7 +735,7 @@ case keyword. It returns nil for the case line itself."
   (go--in-paren-with-prefix-p ?{ ".(type)"))
 
 (defun go--open-paren-position ()
-  "Return non-nil if point is between '(' and ')'.
+  "Return non-nil if point is between `(' and `)'.
 
 The return value is the position of the opening paren."
   (save-excursion
@@ -1655,7 +1655,7 @@ We are looking for the right-hand-side of the type alias"
 (defun go--parameter-list-type (end)
   "Return `present' if the parameter list has names, or `absent' if not.
 Assumes point is at the beginning of a parameter list, just
-after '('."
+after `('."
   (save-excursion
     (skip-chars-forward "[:space:]\n" end)
     (cond ((> (point) end)
@@ -2132,20 +2132,19 @@ code to the Playground. You can disable the confirmation by setting
            (url-request-data
             (encode-coding-string
              (buffer-substring-no-properties start end)
-             'utf-8))
-
-           (content-buf (url-retrieve
-                         "https://play.golang.org/share"
-                         (lambda (arg)
-                           (cond
-                            ((equal :error (car arg))
-                             (signal 'go-play-error (cdr arg)))
-                            (t
-                             (re-search-forward "\n\n")
-                             (let ((url (format "https://play.golang.org/p/%s"
-                                                (buffer-substring (point) (point-max)))))
-                               (when go-play-browse-function
-                                 (funcall go-play-browse-function url))))))))))))
+             'utf-8)))
+      (url-retrieve
+       "https://play.golang.org/share"
+       (lambda (arg)
+         (cond
+          ((equal :error (car arg))
+           (signal 'go-play-error (cdr arg)))
+          (t
+           (re-search-forward "\n\n")
+           (let ((url (format "https://play.golang.org/p/%s"
+                              (buffer-substring (point) (point-max)))))
+             (when go-play-browse-function
+               (funcall go-play-browse-function url))))))))))
 
 ;;;###autoload
 (defun go-download-play (url)
@@ -2472,7 +2471,7 @@ divisor for FILE-NAME."
                (rest (split-string (nth 1 parts) "[., ]")))
 
           (cl-destructuring-bind
-              (start-line start-column end-line end-column num count)
+              (start-line start-column end-line end-column _num count)
               (mapcar #'string-to-number rest)
 
             (when (string= (file-name-nondirectory file) file-name)
@@ -2619,8 +2618,8 @@ If ARG is non-nil, anonymous functions are ignored."
 (defun go-goto-function-name (&optional arg)
   "Go to the name of the current function.
 
-If the function is a test, place point after 'Test'.
-If the function is anonymous, place point on the 'func' keyword.
+If the function is a test, place point after `Test'.
+If the function is anonymous, place point on the `func' keyword.
 
 If ARG is non-nil, anonymous functions are skipped."
   (interactive "P")
diff --git a/go-rename.el b/go-rename.el
index 1f67bb08..b906cc49 100644
--- a/go-rename.el
+++ b/go-rename.el
@@ -1,4 +1,4 @@
-;;; go-rename.el --- Integration of the 'gorename' tool into Emacs.
+;;; go-rename.el --- Integration of the 'gorename' tool into Emacs.  -*- lexical-binding: t; -*-
 
 ;; Copyright 2014 The Go Authors. All rights reserved.
 ;; Use of this source code is governed by a BSD-style
diff --git a/test/go-comment-test.el b/test/go-comment-test.el
index 819fda7d..d75ad20a 100644
--- a/test/go-comment-test.el
+++ b/test/go-comment-test.el
@@ -1,4 +1,4 @@
-;;; go-comment-test.el
+;;; go-comment-test.el  -*- lexical-binding: t; -*-
 
 ;; Copyright 2020 The go-mode Authors. All rights reserved. Use of
 ;; this source code is governed by a BSD-style license that can be
diff --git a/test/go-fill-paragraph-test.el b/test/go-fill-paragraph-test.el
index 6a4a8306..b08e9279 100644
--- a/test/go-fill-paragraph-test.el
+++ b/test/go-fill-paragraph-test.el
@@ -1,4 +1,4 @@
-;;; go-fill-paragraph-test.el
+;;; go-fill-paragraph-test.el  -*- lexical-binding: t; -*-
 
 ;; Copyright 2019 The go-mode Authors.  All rights reserved.
 ;; Use of this source code is governed by a BSD-style
diff --git a/test/go-font-lock-test.el b/test/go-font-lock-test.el
index 3bca76d7..f25a9a0c 100644
--- a/test/go-font-lock-test.el
+++ b/test/go-font-lock-test.el
@@ -1,4 +1,4 @@
-;;; go-font-lock-test.el
+;;; go-font-lock-test.el  -*- lexical-binding: t; -*-
 
 ;; Copyright 2019 The go-mode Authors. All rights reserved. Use of
 ;; this source code is governed by a BSD-style license that can be
diff --git a/test/go-indentation-test.el b/test/go-indentation-test.el
index 8f5d9bc8..8db587bf 100644
--- a/test/go-indentation-test.el
+++ b/test/go-indentation-test.el
@@ -1,4 +1,4 @@
-;;; go-indentation-test.el
+;;; go-indentation-test.el  -*- lexical-binding: t; -*-
 
 ;; Copyright 2019 The go-mode Authors.  All rights reserved.
 ;; Use of this source code is governed by a BSD-style