diff --git a/octopus_energy/rest_client.py b/octopus_energy/rest_client.py
index 3aab1b1..45d521f 100644
--- a/octopus_energy/rest_client.py
+++ b/octopus_energy/rest_client.py
@@ -332,7 +332,7 @@ async def _execute(
         """Executes an API call to Octopus energy and maps the response."""
         url = self.base_url.copy()
         url.path.segments.extend(url_parts)
-        url.query.params.update(query_params)
+        url.query.params.update({p: v for p, v in query_params.items() if v is not None})
         response = await func(url=str(url), **kwargs)
         if response.status > 399:
             if response.status == HTTPStatus.UNAUTHORIZED:
diff --git a/pyproject.toml b/pyproject.toml
index 7050176..3a1ae73 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "octopus-energy"
-version = "0.1.8"
+version = "0.1.9"
 description = "Python client for the Octopus Energy RESTful API"
 authors = ["Mark Allanson <mark@allanson.org>"]
 license = "MIT"