diff --git a/homeassistant/package_constraints.txt b/homeassistant/package_constraints.txt
index d0a192a9dc7b80e388f21b51305419be9d24414b..838c3f31bc56ef8db76a7b71d77e1d3996bca09e 100644
--- a/homeassistant/package_constraints.txt
+++ b/homeassistant/package_constraints.txt
@@ -26,3 +26,7 @@ pycrypto==1000000000.0.0
 
 # Contains code to modify Home Assistant to work around our rules
 python-systemair-savecair==1000000000.0.0
+
+# Newer version causes pylint to take forever
+# https://github.com/timothycrosley/isort/issues/848
+isort==4.3.4
diff --git a/script/gen_requirements_all.py b/script/gen_requirements_all.py
index 47028ef3530f39c4521c334081a40cfff612d119..926aadfc3a557d1031dca09c6e38b35201d378fb 100755
--- a/script/gen_requirements_all.py
+++ b/script/gen_requirements_all.py
@@ -157,6 +157,10 @@ pycrypto==1000000000.0.0
 
 # Contains code to modify Home Assistant to work around our rules
 python-systemair-savecair==1000000000.0.0
+
+# Newer version causes pylint to take forever
+# https://github.com/timothycrosley/isort/issues/848
+isort==4.3.4
 """