diff --git a/bob/devtools/data/conda_build_config.yaml b/bob/devtools/data/conda_build_config.yaml
index bae9bad0f5d403a17463ee74f6db3c63b81b57c1..b30febabef2f5e8c9a0616d8f72fbe78ecca34cf 100644
--- a/bob/devtools/data/conda_build_config.yaml
+++ b/bob/devtools/data/conda_build_config.yaml
@@ -398,7 +398,7 @@ make:
 matplotlib:
   - 3.4.3
 mkl:
-  - 2020.4
+  - 2020.4  # [x86 or x86_64]
 ncurses:
   - 6.2
 nose: