diff --git a/requirements_opt.txt b/requirements_opt.txt
index 0b7478e7..f2b9f91d 100644
--- a/requirements_opt.txt
+++ b/requirements_opt.txt
@@ -1,6 +1,6 @@
 openpyxl
 
-welly
+welly == 0.4.8
 
 # There is an open PR for striplog
 git+https://github.com/Leguark/striplog.git