diff --git a/requirements.txt b/requirements.txt
index 18dbcdc878..66269dac1c 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -28,4 +28,4 @@ trio-typing==0.5.0
 trustme==0.8.0
 uvicorn==0.15.0
 
-attrs>=21.2.0  # See: https://github.com/encode/httpx/pull/566#issuecomment-559862665
+attrs==21.2.0  # See: https://github.com/encode/httpx/pull/566#issuecomment-559862665