diff --git a/doc/erko_howto_tools.txt b/doc/erko_howto_tools.txt
index 14c196ffc5a35e050bee4f20d6ef864ba5787718..fdbb9ae2b7cda20d3332fcd4c28323bb1877df9a 100755
--- a/doc/erko_howto_tools.txt
+++ b/doc/erko_howto_tools.txt
@@ -29,7 +29,7 @@
 * Install OpenSCAD
 * Drawio
 * DTS-lab unb2c
-* Flake8
+* Flake8, black
 
 
 
@@ -1348,9 +1348,13 @@ Alt-F7 to move window on screen
 
 
 *******************************************************************************
-* Flake8
+* Flake8, black
 *******************************************************************************
 
+# gebruik flake8 voor code check, en black als formatter
+# https://flake8.pycqa.org/en/latest/
+# https://pypi.org/project/black/
+
 python3 -m pip install flake8
 
 # add to path in ~/.bashrc