diff --git a/src/HTTPure/Response.purs b/src/HTTPure/Response.purs
index 68b4fd2..0fbc445 100644
--- a/src/HTTPure/Response.purs
+++ b/src/HTTPure/Response.purs
@@ -78,6 +78,7 @@ module HTTPure.Response
 
 import Prelude
 
+import Data.String as String
 import Effect as Effect
 import Effect.Aff as Aff
 import Node.HTTP as HTTP
@@ -104,8 +105,10 @@ type Response =
 send :: HTTP.Response -> Response -> Effect.Effect Unit
 send httpresponse { status, headers, body } = do
   Status.write httpresponse $ status
-  Headers.write httpresponse $ headers
+  Headers.write httpresponse $ headers <> contentLength
   Body.write httpresponse $ body
+  where
+    contentLength = Headers.header "Content-Length" $ show $ String.length body
 
 -- | For custom response statuses or providing a body for response codes that
 -- | don't typically send one.
diff --git a/test/Test/HTTPure/ResponseSpec.purs b/test/Test/HTTPure/ResponseSpec.purs
index 29ba0aa..a96fc6c 100644
--- a/test/Test/HTTPure/ResponseSpec.purs
+++ b/test/Test/HTTPure/ResponseSpec.purs
@@ -19,6 +19,12 @@ sendSpec = Spec.describe "send" do
       Response.send httpResponse mockResponse
       pure $ TestHelpers.getResponseHeader "Test" httpResponse
     header ?= "test"
+  Spec.it "sets the Content-Length header" do
+    header <- EffectClass.liftEffect do
+      httpResponse <- TestHelpers.mockResponse
+      Response.send httpResponse mockResponse
+      pure $ TestHelpers.getResponseHeader "Content-Length" httpResponse
+    header ?= "4"
   Spec.it "writes the status" do
     status <- EffectClass.liftEffect do
       httpResponse <- TestHelpers.mockResponse