diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index a7a373a..f65578a 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -26,9 +26,9 @@ jobs:
       github.repository == 'stainless-sdks/moderation-api-ruby' &&
       (github.event_name == 'push' || github.event.pull_request.head.repo.fork) && (github.event_name != 'push' || github.event.head_commit.message != 'codegen metadata')
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
       - name: Set up Ruby
-        uses: ruby/setup-ruby@v1
+        uses: ruby/setup-ruby@c4e5b1316158f92e3d49443a9d58b31d25ac0f8f # v1.306.0
         with:
           bundler-cache: false
       - run: |-
@@ -39,7 +39,7 @@ jobs:
           github.repository == 'stainless-sdks/moderation-api-ruby' &&
           !startsWith(github.ref, 'refs/heads/stl/')
         id: github-oidc
-        uses: actions/github-script@v8
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8.0.0
         with:
           script: core.setOutput('github_token', await core.getIDToken());
 
@@ -60,9 +60,9 @@ jobs:
     if: github.event_name == 'push' || github.event.pull_request.head.repo.fork
 
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
       - name: Set up Ruby
-        uses: ruby/setup-ruby@v1
+        uses: ruby/setup-ruby@c4e5b1316158f92e3d49443a9d58b31d25ac0f8f # v1.306.0
         with:
           bundler-cache: false
       - run: |-
@@ -76,9 +76,9 @@ jobs:
     runs-on: ${{ github.repository == 'stainless-sdks/moderation-api-ruby' && 'depot-ubuntu-24.04' || 'ubuntu-latest' }}
     if: github.event_name == 'push' || github.event.pull_request.head.repo.fork
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
       - name: Set up Ruby
-        uses: ruby/setup-ruby@v1
+        uses: ruby/setup-ruby@c4e5b1316158f92e3d49443a9d58b31d25ac0f8f # v1.306.0
         with:
           bundler-cache: false
       - run: |-
diff --git a/.github/workflows/publish-gem.yml b/.github/workflows/publish-gem.yml
index ff8587a..4fea895 100644
--- a/.github/workflows/publish-gem.yml
+++ b/.github/workflows/publish-gem.yml
@@ -14,9 +14,9 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
       - name: Set up Ruby
-        uses: ruby/setup-ruby@v1
+        uses: ruby/setup-ruby@c4e5b1316158f92e3d49443a9d58b31d25ac0f8f # v1.306.0
         with:
           bundler-cache: false
       - run: |-
diff --git a/.github/workflows/release-doctor.yml b/.github/workflows/release-doctor.yml
index 9647c9e..74d392a 100644
--- a/.github/workflows/release-doctor.yml
+++ b/.github/workflows/release-doctor.yml
@@ -12,7 +12,7 @@ jobs:
     if: github.repository == 'moderation-api/sdk-ruby' && (github.event_name == 'push' || github.event_name == 'workflow_dispatch' || startsWith(github.head_ref, 'release-please') || github.head_ref == 'next')
 
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
 
       - name: Check release environment
         run: |
diff --git a/.release-please-manifest.json b/.release-please-manifest.json
index c1a7e63..bc4724b 100644
--- a/.release-please-manifest.json
+++ b/.release-please-manifest.json
@@ -1,3 +1,3 @@
 {
-  ".": "2.17.0"
+  ".": "2.17.1"
 }
\ No newline at end of file
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 00e1aee..4098098 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,13 @@
 # Changelog
 
+## 2.17.1 (2026-05-14)
+
+Full Changelog: [v2.17.0...v2.17.1](https://github.com/moderation-api/sdk-ruby/compare/v2.17.0...v2.17.1)
+
+### Bug Fixes
+
+* **client:** elide content type header on requests without body ([c1a43a0](https://github.com/moderation-api/sdk-ruby/commit/c1a43a0212bdaf1c7f81e2c56c961e49e4830e61))
+
 ## 2.17.0 (2026-05-08)
 
 Full Changelog: [v2.16.0...v2.17.0](https://github.com/moderation-api/sdk-ruby/compare/v2.16.0...v2.17.0)
diff --git a/Gemfile.lock b/Gemfile.lock
index 4730da6..3e4c4c7 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -11,7 +11,7 @@ GIT
 PATH
   remote: .
   specs:
-    moderation_api (2.17.0)
+    moderation_api (2.17.1)
       cgi
       connection_pool
 
diff --git a/README.md b/README.md
index 02285ff..d9080b7 100644
--- a/README.md
+++ b/README.md
@@ -15,7 +15,7 @@ To use this gem, install via Bundler by adding the following to your application
 <!-- x-release-please-start-version -->
 
 ```ruby
-gem "moderation_api", "~> 2.17.0"
+gem "moderation_api", "~> 2.17.1"
 ```
 
 <!-- x-release-please-end -->
diff --git a/lib/moderation_api/internal/transport/base_client.rb b/lib/moderation_api/internal/transport/base_client.rb
index 27bc8ea..0dc56d9 100644
--- a/lib/moderation_api/internal/transport/base_client.rb
+++ b/lib/moderation_api/internal/transport/base_client.rb
@@ -306,6 +306,8 @@ def initialize(
               ModerationAPI::Internal::Util.deep_merge(*[req[:body], opts[:extra_body]].compact)
             end
 
+          headers.delete("content-type") if body.nil?
+
           url = ModerationAPI::Internal::Util.join_parsed_uri(
             @base_url_components,
             {**req, path: path, query: query}
diff --git a/lib/moderation_api/version.rb b/lib/moderation_api/version.rb
index 7df3aa9..846b8d8 100644
--- a/lib/moderation_api/version.rb
+++ b/lib/moderation_api/version.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module ModerationAPI
-  VERSION = "2.17.0"
+  VERSION = "2.17.1"
 end
diff --git a/test/moderation_api/client_test.rb b/test/moderation_api/client_test.rb
index 04e2568..23b5dcc 100644
--- a/test/moderation_api/client_test.rb
+++ b/test/moderation_api/client_test.rb
@@ -211,8 +211,8 @@ def test_client_redirect_307
       assert_equal(recorded.method, _1.method)
       assert_equal(recorded.body, _1.body)
       assert_equal(
-        recorded.headers.transform_keys(&:downcase).fetch("content-type"),
-        _1.headers.transform_keys(&:downcase).fetch("content-type")
+        recorded.headers.transform_keys(&:downcase)["content-type"],
+        _1.headers.transform_keys(&:downcase)["content-type"]
       )
     end
   end
@@ -305,8 +305,9 @@ def test_default_headers
     moderation_api.content.submit(content: {text: "x", type: :text})
 
     assert_requested(:any, /./) do |req|
-      headers = req.headers.transform_keys(&:downcase).fetch_values("accept", "content-type")
-      headers.each { refute_empty(_1) }
+      headers = req.headers.transform_keys(&:downcase)
+      expected = req.body.nil? ? ["accept"] : %w[accept content-type]
+      headers.fetch_values(*expected).each { refute_empty(_1) }
     end
   end
 end