diff --git a/moto/awslambda/models.py b/moto/awslambda/models.py
index f2400ec38..a1643cd03 100644
--- a/moto/awslambda/models.py
+++ b/moto/awslambda/models.py
@@ -292,22 +292,24 @@ class LambdaFunction(BaseModel):
 
         return self.get_configuration()
 
-    def update_function_code(self, spec):
-        if 'DryRun' in spec and spec['DryRun']:
+    def update_function_code(self, updated_spec):
+        if 'DryRun' in updated_spec and updated_spec['DryRun']:
             return self.get_configuration()
 
-        if 'Publish' in spec and spec['Publish']:
+        if 'Publish' in updated_spec and updated_spec['Publish']:
             self.set_version(self.version + 1)
 
-        if 'ZipFile' in spec:
-            # using the "hackery" from __init__" because it seems to work
+        if 'ZipFile' in updated_spec:
+            self.code['ZipFile'] = updated_spec['ZipFile']
+
+            # using the "hackery" from __init__ because it seems to work
             # TODOs and FIXMEs included, because they'll need to be fixed
             # in both places now
             try:
                 to_unzip_code = base64.b64decode(
-                    bytes(spec['ZipFile'], 'utf-8'))
+                    bytes(updated_spec['ZipFile'], 'utf-8'))
             except Exception:
-                to_unzip_code = base64.b64decode(spec['ZipFile'])
+                to_unzip_code = base64.b64decode(updated_spec['ZipFile'])
 
             self.code_bytes = to_unzip_code
             self.code_size = len(to_unzip_code)
@@ -316,11 +318,11 @@ class LambdaFunction(BaseModel):
             # TODO: we should be putting this in a lambda bucket
             self.code['UUID'] = str(uuid.uuid4())
             self.code['S3Key'] = '{}-{}'.format(self.function_name, self.code['UUID'])
-        else:
+        elif 'S3Bucket' in updated_spec and 'S3Key' in updated_spec:
             key = None
             try:
                 # FIXME: does not validate bucket region
-                key = s3_backend.get_key(spec['S3Bucket'], spec['S3Key'])
+                key = s3_backend.get_key(updated_spec['S3Bucket'], updated_spec['S3Key'])
             except MissingBucket:
                 if do_validate_s3():
                     raise ValueError(
diff --git a/moto/awslambda/responses.py b/moto/awslambda/responses.py
index e22fee152..2041aa660 100644
--- a/moto/awslambda/responses.py
+++ b/moto/awslambda/responses.py
@@ -123,14 +123,16 @@ class LambdaResponse(BaseResponse):
             return self._add_policy(request, full_url, headers)
 
     def configuration(self, request, full_url, headers):
+        self.setup_class(request, full_url, headers)
         if request.method == 'PUT':
-            return self._put_configuration(request, full_url)
+            return self._put_configuration(request)
         else:
             raise ValueError("Cannot handle request")
 
     def code(self, request, full_url, headers):
+        self.setup_class(request, full_url, headers)
         if request.method == 'PUT':
-            return self._put_code(request, full_url, headers)
+            return self._put_code()
         else:
             raise ValueError("Cannot handle request")
 
@@ -321,26 +323,26 @@ class LambdaResponse(BaseResponse):
         else:
             return 404, {}, "{}"
 
-    def _put_configuration(self, request, full_url):
-        function_name = self._get_param('FunctionName', None)
+    def _put_configuration(self, request):
+        function_name = self.path.rsplit('/', 2)[-2]
         qualifier = self._get_param('Qualifier', None)
 
         fn = self.lambda_backend.get_function(function_name, qualifier)
 
         if fn:
-            config = fn.update_configuration(json.loads(request.body))
+            config = fn.update_configuration(self.json_body)
             return 200, {}, json.dumps(config)
         else:
             return 404, {}, "{}"
 
-    def _put_code(self, request, full_url, headers):
-        function_name = self._get_param('FunctionName', None)
+    def _put_code(self):
+        function_name = self.path.rsplit('/', 2)[-2]
         qualifier = self._get_param('Qualifier', None)
 
         fn = self.lambda_backend.get_function(function_name, qualifier)
 
         if fn:
-            config = fn.update_function_code(json.loads(request.body))
+            config = fn.update_function_code(self.json_body)
             return 200, {}, json.dumps(config)
         else:
             return 404, {}, "{}"
diff --git a/tests/test_awslambda/test_lambda.py b/tests/test_awslambda/test_lambda.py
index 0a6df7cca..20a806de2 100644
--- a/tests/test_awslambda/test_lambda.py
+++ b/tests/test_awslambda/test_lambda.py
@@ -1295,7 +1295,6 @@ def test_update_configuration():
 
 
 @mock_lambda
-@freeze_time('2015-01-01 00:00:00')
 def test_update_function():
     conn = boto3.client('lambda', 'us-west-2')
 
@@ -1317,7 +1316,7 @@ def test_update_function():
 
     zip_content_two = get_test_zip_file2()
 
-    conn.update_function_code(
+    fxn_updated = conn.update_function_code(
         FunctionName='testFunction',
         ZipFile=zip_content_two,
         Publish=True