diff --git a/lower-constraints.txt b/lower-constraints.txt
index 0672190c3f9..7eaa6257e7d 100644
--- a/lower-constraints.txt
+++ b/lower-constraints.txt
@@ -31,6 +31,7 @@ greenlet==0.4.10
 httplib2==0.9.1
 imagesize==0.7.1
 iso8601==0.1.11
+isort==4.3.21
 Jinja2==2.10
 jmespath==0.9.0
 jsonpatch==1.16
diff --git a/test-requirements.txt b/test-requirements.txt
index 3622b7f2d4b..288bdd8b593 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -19,6 +19,7 @@ astroid==1.6.5;python_version<"3.0" # LGPLv2.1
 astroid==2.1.0;python_version>="3.0" # LGPLv2.1
 pylint==1.9.2;python_version<"3.0" # GPLv2
 pylint==2.2.0;python_version>="3.0" # GPLv2
+isort==4.3.21 # MIT
 # Needed to run DB commands in virtualenvs
 PyMySQL>=0.7.6 # MIT License
 bashate>=0.5.1 # Apache-2.0