diff --git a/requirements.txt b/requirements.txt
index e6e63d63..9d99d1bb 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -5,6 +5,7 @@ binaryornot==0.4.4
 # Code quality
 # ------------------------------------------------------------------------------
 black==19.10b0
+isort==4.3.21
 flake8==3.8.3
 flake8-isort==3.0.0