diff --git a/.github/workflows/test-external.yaml b/.github/workflows/test-external.yaml
index d55882cea..bcf7a6c72 100644
--- a/.github/workflows/test-external.yaml
+++ b/.github/workflows/test-external.yaml
@@ -11,7 +11,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest]
-        ruby: ['2.7', '3.0', '3.1']
+        ruby: ['3.0', '3.1', '3.2', '3.3']
 
     runs-on: ${{matrix.os}}
 
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 09a7aa440..c1f38daf6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,16 @@
 
 All notable changes to this project will be documented in this file. For info on how to format all future additions to this file please reference [Keep A Changelog](https://keepachangelog.com/en/1.0.0/).
 
+## Unreleased
+
+## [3.0.9] - 2024-01-31
+
+- Fix incorrect content-length header that was emitted when `Rack::Response#write` was used in some situations. ([#2150](https://github.com/rack/rack/pull/2150), [@mattbrictson])
+
+## [3.0.8] - 2023-06-14
+
+- Fix some unused variable verbose warnings. ([#2084](https://github.com/rack/rack/pull/2084), [@jeremyevans], [@skipkayhil](https://github.com/skipkayhil))
+
 ## [3.0.7] - 2023-03-16
 
 - Make query parameters without `=` have `nil` values. ([#2059](https://github.com/rack/rack/pull/2059), [@jeremyevans])
diff --git a/lib/rack/response.rb b/lib/rack/response.rb
index f24683bcb..b9b02c272 100644
--- a/lib/rack/response.rb
+++ b/lib/rack/response.rb
@@ -328,6 +328,8 @@ def buffered_body!
             @body.each do |part|
               @length += part.to_s.bytesize
             end
+
+            @buffered = true
           elsif @body.respond_to?(:each)
             # Turn the user supplied body into a buffered array:
             body = @body
diff --git a/lib/rack/version.rb b/lib/rack/version.rb
index e634f23ae..e2deadab2 100644
--- a/lib/rack/version.rb
+++ b/lib/rack/version.rb
@@ -25,7 +25,7 @@ def self.version
     VERSION
   end
 
-  RELEASE = "3.0.8"
+  RELEASE = "3.0.9"
 
   # Return the Rack release as a dotted string.
   def self.release
diff --git a/test/spec_response.rb b/test/spec_response.rb
index ef8aa481c..11e64d61f 100644
--- a/test/spec_response.rb
+++ b/test/spec_response.rb
@@ -412,7 +412,7 @@ def object_with_each.each
     status.must_equal 404
   end
 
-  it "correctly updates content-type when writing when not initialized with body" do
+  it "correctly updates content-length when writing when initialized without body" do
     r = Rack::Response.new
     r.write('foo')
     r.write('bar')
@@ -423,20 +423,39 @@ def object_with_each.each
     header['content-length'].must_equal '9'
   end
 
-  it "correctly updates content-type when writing when initialized with body" do
+  it "correctly updates content-length when writing when initialized with Array body" do
+    r = Rack::Response.new(["foo"])
+    r.write('bar')
+    r.write('baz')
+    _, header, body = r.finish
+    str = "".dup; body.each { |part| str << part }
+    str.must_equal "foobarbaz"
+    header['content-length'].must_equal '9'
+  end
+
+  it "correctly updates content-length when writing when initialized with String body" do
+    r = Rack::Response.new("foo")
+    r.write('bar')
+    r.write('baz')
+    _, header, body = r.finish
+    str = "".dup; body.each { |part| str << part }
+    str.must_equal "foobarbaz"
+    header['content-length'].must_equal '9'
+  end
+
+  it "correctly updates content-length when writing when initialized with object body that responds to #each" do
     obj = Object.new
     def obj.each
       yield 'foo'
       yield 'bar'
     end
-    ["foobar", ["foo", "bar"], obj].each do
-      r = Rack::Response.new(["foo", "bar"])
-      r.write('baz')
-      _, header, body = r.finish
-      str = "".dup; body.each { |part| str << part }
-      str.must_equal "foobarbaz"
-      header['content-length'].must_equal '9'
-    end
+    r = Rack::Response.new(obj)
+    r.write('baz')
+    r.write('baz')
+    _, header, body = r.finish
+    str = "".dup; body.each { |part| str << part }
+    str.must_equal "foobarbazbaz"
+    header['content-length'].must_equal '12'
   end
 
   it "doesn't return invalid responses" do