diff --git a/src/Tools/blocFissure/doc/conf.py.in b/src/Tools/blocFissure/doc/conf.py.in
index 07f6864d3..5f2db165d 100644
--- a/src/Tools/blocFissure/doc/conf.py.in
+++ b/src/Tools/blocFissure/doc/conf.py.in
@@ -12,6 +12,7 @@
 # serve to show the default value.
 
 import sys, os
+import sphinx
 
 # If your extensions are in another directory, add it here. If the directory
 # is relative to the documentation root, use os.path.abspath to make it