diff --git a/environment.yml b/environment.yml
index 2429f4ab3d699..24c0832b6fb4c 100644
--- a/environment.yml
+++ b/environment.yml
@@ -20,7 +20,7 @@ dependencies:
   - flake8<3.8.0  # temporary pin, GH#34150
   - flake8-comprehensions>=3.1.0  # used by flake8, linting of unnecessary comprehensions
   - flake8-rst>=0.6.0,<=0.7.0  # linting of code blocks in rst files
-  - isort  # check that imports are in the right order
+  - isort=4.3.21  # check that imports are in the right order
   - mypy=0.730
   - pycodestyle  # used by flake8
 
diff --git a/requirements-dev.txt b/requirements-dev.txt
index 44c975a3b3cfb..eda0fa8f32b19 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -11,7 +11,7 @@ cpplint
 flake8<3.8.0
 flake8-comprehensions>=3.1.0
 flake8-rst>=0.6.0,<=0.7.0
-isort
+isort==4.3.21
 mypy==0.730
 pycodestyle
 gitpython