diff --git a/.release-please-manifest.json b/.release-please-manifest.json
index 1eec10e9..f1a48d37 100644
--- a/.release-please-manifest.json
+++ b/.release-please-manifest.json
@@ -1,3 +1,3 @@
 {
-  ".": "4.7.0"
+  ".": "4.7.1"
 }
\ No newline at end of file
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 373589be..f93bae61 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,13 @@
 # Changelog
 
+## 4.7.1 (2026-02-07)
+
+Full Changelog: [v4.7.0...v4.7.1](https://github.com/trycourier/courier-ruby/compare/v4.7.0...v4.7.1)
+
+### Bug Fixes
+
+* **client:** loosen json header parsing ([70d1c0d](https://github.com/trycourier/courier-ruby/commit/70d1c0d55a6982b059be2809cae088351ba7f112))
+
 ## 4.7.0 (2026-02-06)
 
 Full Changelog: [v4.6.3...v4.7.0](https://github.com/trycourier/courier-ruby/compare/v4.6.3...v4.7.0)
diff --git a/Gemfile.lock b/Gemfile.lock
index c0b0364f..e0b6500b 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -11,7 +11,7 @@ GIT
 PATH
   remote: .
   specs:
-    trycourier (4.7.0)
+    trycourier (4.7.1)
       cgi
       connection_pool
 
diff --git a/README.md b/README.md
index 9c8eb441..3e2c2646 100644
--- a/README.md
+++ b/README.md
@@ -17,7 +17,7 @@ To use this gem, install via Bundler by adding the following to your application
 <!-- x-release-please-start-version -->
 
 ```ruby
-gem "trycourier", "~> 4.7.0"
+gem "trycourier", "~> 4.7.1"
 ```
 
 <!-- x-release-please-end -->
diff --git a/lib/courier/internal/util.rb b/lib/courier/internal/util.rb
index fc0a2c77..e49292ae 100644
--- a/lib/courier/internal/util.rb
+++ b/lib/courier/internal/util.rb
@@ -485,7 +485,7 @@ def writable_enum(&blk)
       end
 
       # @type [Regexp]
-      JSON_CONTENT = %r{^application/(?:vnd(?:\.[^.]+)*\+)?json(?!l)}
+      JSON_CONTENT = %r{^application/(?:[a-zA-Z0-9.-]+\+)?json(?!l)}
       # @type [Regexp]
       JSONL_CONTENT = %r{^application/(:?x-(?:n|l)djson)|(:?(?:x-)?jsonl)}
 
diff --git a/lib/courier/version.rb b/lib/courier/version.rb
index 006c4e58..4ef2cb5e 100644
--- a/lib/courier/version.rb
+++ b/lib/courier/version.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module Courier
-  VERSION = "4.7.0"
+  VERSION = "4.7.1"
 end
diff --git a/rbi/courier/internal/util.rbi b/rbi/courier/internal/util.rbi
index 97cb71f7..5d0a35f9 100644
--- a/rbi/courier/internal/util.rbi
+++ b/rbi/courier/internal/util.rbi
@@ -296,7 +296,7 @@ module Courier
       end
 
       JSON_CONTENT =
-        T.let(%r{^application/(?:vnd(?:\.[^.]+)*\+)?json(?!l)}, Regexp)
+        T.let(%r{^application/(?:[a-zA-Z0-9.-]+\+)?json(?!l)}, Regexp)
       JSONL_CONTENT =
         T.let(%r{^application/(:?x-(?:n|l)djson)|(:?(?:x-)?jsonl)}, Regexp)
 
diff --git a/test/courier/internal/util_test.rb b/test/courier/internal/util_test.rb
index 5584ef84..c4dd2b16 100644
--- a/test/courier/internal/util_test.rb
+++ b/test/courier/internal/util_test.rb
@@ -171,6 +171,8 @@ def test_json_content
     cases = {
       "application/json" => true,
       "application/jsonl" => false,
+      "application/arbitrary+json" => true,
+      "application/ARBITRARY+json" => true,
       "application/vnd.github.v3+json" => true,
       "application/vnd.api+json" => true
     }