diff --git a/requirements/ci.txt b/requirements/ci.txt
index 05d75087..b1d8ecdd 100644
--- a/requirements/ci.txt
+++ b/requirements/ci.txt
@@ -6,7 +6,8 @@ pyupgrade==3.1.0;python_version>"3.6"  # https://github.com/asottile/pyupgrade
 # Code quality
 # ------------------------------------------------------------------------------
 flake8==5.0.4  # https://github.com/PyCQA/flake8
-flake8-isort==5.0.0  # https://github.com/gforcada/flake8-isort
+flake8-isort==5.0.0;python_version>"3.6"  # https://github.com/gforcada/flake8-isort
+flake8-isort<=4.2.0;python_version<="3.6"
 flake8-bugbear==22.9.23  # https://github.com/PyCQA/flake8-bugbear
 flake8-pyi==22.10.0;python_version>"3.6"  # https://github.com/ambv/flake8-pyi
 flake8-pyi<20.10;python_version<="3.6"