diff --git a/core/src/main/java/feign/DefaultClient.java b/core/src/main/java/feign/DefaultClient.java
index d8e02fb4ad..0ab6bf10ae 100644
--- a/core/src/main/java/feign/DefaultClient.java
+++ b/core/src/main/java/feign/DefaultClient.java
@@ -218,7 +218,9 @@ else if (field.equals(ACCEPT_ENCODING)) {
       }
     }
 
-    if (body == null && request.httpMethod().isWithBody()) {
+    if (body == null
+        && request.httpMethod().isWithBody()
+        && !request.headers().containsKey(CONTENT_LENGTH)) {
       // To use this Header, set 'sun.net.http.allowRestrictedHeaders' property true.
       connection.addRequestProperty("Content-Length", "0");
     }
diff --git a/core/src/test/java/feign/client/DefaultClientTest.java b/core/src/test/java/feign/client/DefaultClientTest.java
index c61b1b0a4d..6f84acee9d 100644
--- a/core/src/test/java/feign/client/DefaultClientTest.java
+++ b/core/src/test/java/feign/client/DefaultClientTest.java
@@ -24,6 +24,8 @@
 import feign.DefaultClient;
 import feign.Feign;
 import feign.Feign.Builder;
+import feign.Headers;
+import feign.RequestLine;
 import feign.RetryableException;
 import feign.assertj.MockWebServerAssertions;
 import java.io.IOException;
@@ -101,6 +103,25 @@ public void noRequestBodyForPostWithAllowRestrictedHeaders() throws Exception {
         .hasHeaders(entry("Content-Length", Collections.singletonList("0")));
   }
 
+  @Test
+  @EnabledIfSystemProperty(named = "sun.net.http.allowRestrictedHeaders", matches = "true")
+  public void contentLengthHeaderIsNotDuplicatedForBodylessRequest() throws Exception {
+    server.enqueue(new MockResponse());
+
+    ContentLengthInterface api =
+        newBuilder().target(ContentLengthInterface.class, "http://localhost:" + server.getPort());
+
+    api.postEmpty();
+
+    assertThat(server.takeRequest().getHeaders().values("Content-Length")).containsExactly("0");
+  }
+
+  interface ContentLengthInterface {
+    @RequestLine("POST /")
+    @Headers("Content-Length: 0")
+    void postEmpty();
+  }
+
   @Test
   @Override
   public void noResponseBodyForPut() throws Exception {