diff --git a/pyproject.toml b/pyproject.toml
index fb9f0453..1395ce82 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -28,7 +28,7 @@ dependencies = [
     "click-default-group>=1.2.3",
     "Jinja2>=2.10.3",
     "hupper>=1.9",
-    "httpx>=0.20",
+    "httpx>=0.20,<1.0",
     "pluggy>=1.0",
     "uvicorn>=0.11",
     "aiofiles>=0.4",