diff --git a/moto/s3/responses.py b/moto/s3/responses.py
index 4f8e6e993..a2c0f3dd5 100644
--- a/moto/s3/responses.py
+++ b/moto/s3/responses.py
@@ -294,6 +294,8 @@ class ResponseObject(_TemplateEnvironmentMixin):
         )
 
     def _bucket_response_put(self, request, body, region_name, bucket_name, querystring, headers):
+        if not request.headers.get('Content-Length'):
+            return 411, {}, "Content-Length required"
         if 'versioning' in querystring:
             ver = re.search('<Status>([A-Za-z]+)</Status>', body)
             if ver:
@@ -355,6 +357,8 @@ class ResponseObject(_TemplateEnvironmentMixin):
             return 409, {}, template.render(bucket=removed_bucket)
 
     def _bucket_response_post(self, request, body, bucket_name, headers):
+        if not request.headers.get('Content-Length'):
+            return 411, {}, "Content-Length required"
         path = request.path if hasattr(request, 'path') else request.path_url
         if self.is_delete_keys(request, path, bucket_name):
             return self._bucket_response_delete_keys(request, body, bucket_name, headers)
diff --git a/tests/test_s3/test_server.py b/tests/test_s3/test_server.py
index f6b8f889c..e0440ce2f 100644
--- a/tests/test_s3/test_server.py
+++ b/tests/test_s3/test_server.py
@@ -66,3 +66,14 @@ def test_s3_server_post_to_bucket():
     res = test_client.get('/the-key', 'http://tester.localhost:5000/')
     res.status_code.should.equal(200)
     res.data.should.equal(b"nothing")
+
+
+def test_s3_server_post_without_content_length():
+    backend = server.create_backend_app("s3")
+    test_client = backend.test_client()
+
+    res = test_client.put('/', 'http://tester.localhost:5000/', environ_overrides={'CONTENT_LENGTH': ''})
+    res.status_code.should.equal(411)
+
+    res = test_client.post('/', "https://tester.localhost:5000/", environ_overrides={'CONTENT_LENGTH': ''})
+    res.status_code.should.equal(411)