diff --git a/bob/devtools/data/conda_build_config.yaml b/bob/devtools/data/conda_build_config.yaml
index 3666d8de93798ba92cb96430264b3e08d67ed3d9..58e8b4a7a5eccf070848107b77408f4e74243029 100644
--- a/bob/devtools/data/conda_build_config.yaml
+++ b/bob/devtools/data/conda_build_config.yaml
@@ -202,6 +202,8 @@ setuptools:
   - 50.3.0
 simplejson:
   - 3.17.2
+six:
+  - 1
 sphinx:
   - 3.2.1
 sphinx_rtd_theme: