diff --git a/pyproject.toml b/pyproject.toml
index 45055b9..82224ff 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -43,7 +43,7 @@ dynamic = [
   "version",
 ]
 dependencies = [
-  "httpx>=0.27",
+  "httpx<0.28",   # this is pinned temporarily, until respx is able to mock 0.28+ properly
   "xsdata>=24.5",
 ]
 optional-dependencies.cli = [