diff --git a/lib/git_client.rb b/lib/git_client.rb
index ab11115..31614a2 100644
--- a/lib/git_client.rb
+++ b/lib/git_client.rb
@@ -37,8 +37,10 @@ def checkout_fresh_branch(branch:, base:)
     # Returns true iff a commit was actually created; false when
     # bin/importmap pin was a no-op and there is nothing to commit.
     def commit_changes(message:)
+      @repo.config("user.name", @author_name)
+      @repo.config("user.email", @author_email)
       @repo.add(["config/importmap.rb", "vendor/javascript"])
-      @repo.commit(message, author: "#{@author_name} <#{@author_email}>")
+      @repo.commit(message)
       true
     rescue Git::FailedError => e
       return false if e.result.stderr.to_s.include?("nothing to commit")
diff --git a/test/git_client_test.rb b/test/git_client_test.rb
index af4ff01..181a710 100644
--- a/test/git_client_test.rb
+++ b/test/git_client_test.rb
@@ -10,7 +10,6 @@ class GitClientTest < Minitest::Test
 
   AUTHOR_NAME = "Test Bot"
   AUTHOR_EMAIL = "bot@example.com"
-  AUTHOR_STRING = "Test Bot <bot@example.com>"
 
   def setup
     @repo = Minitest::Mock.new
@@ -44,14 +43,17 @@ def test_checkout_fresh_branch_resets_existing_branch_to_base
 
   def test_commit_changes_stages_and_commits_returning_true
     @repo.expect(:add, nil, [["config/importmap.rb", "vendor/javascript"]])
-    @repo.expect(:commit, nil, ["Bump lodash from 4.17.20 to 4.17.21"],
-      author: AUTHOR_STRING)
+    @repo.expect(:config, nil, ["user.name", AUTHOR_NAME])
+    @repo.expect(:config, nil, ["user.email", AUTHOR_EMAIL])
+    @repo.expect(:commit, nil, ["Bump lodash from 4.17.20 to 4.17.21"])
 
     assert_equal true, @client.commit_changes(message: "Bump lodash from 4.17.20 to 4.17.21")
   end
 
   def test_commit_changes_returns_false_when_nothing_to_commit
     @repo.expect(:add, nil, [["config/importmap.rb", "vendor/javascript"]])
+    @repo.expect(:config, nil, ["user.name", AUTHOR_NAME])
+    @repo.expect(:config, nil, ["user.email", AUTHOR_EMAIL])
     @repo.expect(:commit, nil) do |_msg, **_opts|
       raise git_failed_error("nothing to commit, working tree clean")
     end
@@ -61,6 +63,8 @@ def test_commit_changes_returns_false_when_nothing_to_commit
 
   def test_commit_changes_re_raises_unexpected_git_errors
     @repo.expect(:add, nil, [["config/importmap.rb", "vendor/javascript"]])
+    @repo.expect(:config, nil, ["user.name", AUTHOR_NAME])
+    @repo.expect(:config, nil, ["user.email", AUTHOR_EMAIL])
     @repo.expect(:commit, nil) do |_msg, **_opts|
       raise git_failed_error("lock file exists")
     end