diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index a1810ea..fe477df 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -14,7 +14,7 @@ repos:
       - id: trailing-whitespace
 
   - repo: https://github.com/psf/black
-    rev: 20.8b1
+    rev: 22.3.0
     hooks:
       - id: black
 
diff --git a/Makefile b/Makefile
index 5848ef0..2eb3dbe 100644
--- a/Makefile
+++ b/Makefile
@@ -46,7 +46,7 @@ flake8: install-dev
 	$(VENV)/bin/flake8 setup.py alma tests
 
 mypy: install-dev
-	$(VENV)/bin/mypy --ignore-missing-imports --scripts-are-modules alma
+	$(VENV)/bin/mypy --ignore-missing-imports --scripts-are-modules --implicit-optional alma
 
 build-requirements:
 	$(VIRTUALENV) $(TEMPDIR)
diff --git a/alma_client/async_client.py b/alma_client/async_client.py
index 126ce2e..dfcecad 100644
--- a/alma_client/async_client.py
+++ b/alma_client/async_client.py
@@ -9,14 +9,8 @@
 
 
 async def process_request(req):
-    request = httpx.Request(
-        req.method,
-        req.url,
-        headers=req.headers,
-        cookies=req.cookies,
-        params=req.params,
-        json=req.body,
-    )
+
+    request = req.to_httpx()
     async with httpx.AsyncClient() as client:
         resp = await client.send(request)
 
diff --git a/alma_client/client.py b/alma_client/client.py
index 234ff97..ccef6e2 100644
--- a/alma_client/client.py
+++ b/alma_client/client.py
@@ -20,14 +20,8 @@
 
 
 def process_request(req):
-    request = httpx.Request(
-        req.method,
-        req.url,
-        headers=req.headers,
-        cookies=req.cookies,
-        params=req.params,
-        json=req.body,
-    )
+
+    request = req.to_httpx()
     with httpx.Client() as client:
         resp = client.send(request)
 
diff --git a/alma_client/request.py b/alma_client/request.py
index 670c5ea..799b5df 100644
--- a/alma_client/request.py
+++ b/alma_client/request.py
@@ -1,18 +1,8 @@
-from functools import wraps
+import json
 
-from .paginated_results import PaginatedResults
-
-
-def configure_credentials(func):
-    def decorator(f):
-        @wraps(f)
-        def decorated(request, *args, **kwargs):
-            request.context.credentials.configure(request)
-            return f(request, *args, **kwargs)
+import httpx
 
-        return decorated
-
-    return decorator(func)
+from .paginated_results import PaginatedResults
 
 
 class RequestError(Exception):
@@ -58,22 +48,36 @@ def expectPaginatedList(self, cls, next_page):
         self.response_processor = lambda response: PaginatedResults(response.json, cls, next_page)
         return self
 
-    @configure_credentials
     def get(self):
         self.method = "GET"
         return self
 
-    @configure_credentials
     def post(self):
         self.method = "POST"
         return self
 
-    @configure_credentials
     def put(self):
         self.method = "PUT"
         return self
 
-    @configure_credentials
     def delete(self):
         self.method = "DELETE"
         return self
+
+    @property
+    def data(self):
+        return json.dumps(self.body)
+
+    def to_httpx(self):
+        self.context.credentials.configure(self)
+        headers = self.headers.copy()
+        headers["Content-Type"] = "application/json"
+        req = httpx.Request(
+            self.method,
+            self.url,
+            headers=headers,
+            cookies=self.cookies,
+            params=self.params,
+            content=self.data,
+        )
+        return req
diff --git a/setup.py b/setup.py
index b3ca196..9466938 100644
--- a/setup.py
+++ b/setup.py
@@ -12,7 +12,7 @@
 # This call to setup() does all the work
 setup(
     name="alma-client",
-    version="3.1.0.dev0",
+    version="3.2.0",
     description="Python API client for the Alma Installments API",
     long_description=f"{README}\n\n{CHANGELOG}",
     long_description_content_type="text/markdown",
diff --git a/tests/test_request.py b/tests/test_request.py
index 3c4ad96..9abc6a1 100644
--- a/tests/test_request.py
+++ b/tests/test_request.py
@@ -10,19 +10,10 @@ def setUp(self) -> None:
         self.credentials = client.context.credentials
         self.request = Request(client.context, "https://url.com")
 
-    def assert_method_calls_configure(self, method):
+    def test_credentials_configure_is_called_on_request_build(self):
         with mock.patch("alma_client.credentials.ApiKeyCredentials.configure") as mocked_configure:
-            getattr(self.request, method)()
+            self.request.get()
+            mocked_configure.assert_not_called()
+            # only upon building the httpx Req are the credentials configured
+            _ = self.request.to_httpx()
             mocked_configure.assert_called_once_with(self.request)
-
-    def test_credentials_configure_is_called_on_get(self):
-        self.assert_method_calls_configure("get")
-
-    def test_credentials_configure_is_called_on_post(self):
-        self.assert_method_calls_configure("post")
-
-    def test_credentials_configure_is_called_on_put(self):
-        self.assert_method_calls_configure("put")
-
-    def test_credentials_configure_is_called_on_delete(self):
-        self.assert_method_calls_configure("delete")
diff --git a/tox.ini b/tox.ini
index 82a1007..49bedac 100644
--- a/tox.ini
+++ b/tox.ini
@@ -9,7 +9,7 @@ python =
 
 [testenv]
 commands =
-    mypy --ignore-missing-imports --scripts-are-modules alma_client
+    mypy --ignore-missing-imports --scripts-are-modules --implicit-optional alma_client
     pytest tests --cov-report term-missing --cov alma_client {posargs} # --cov-fail-under 100
 deps =
     -rtest-requirements.txt