diff --git a/software/ipython_notebook/instance.cfg.in b/software/ipython_notebook/instance.cfg.in
index 24a5f1bfc0c34e290162aa186014a3b2186de627..4a5946ad1312d851b9a05317aa168c57fd93a719 100644
--- a/software/ipython_notebook/instance.cfg.in
+++ b/software/ipython_notebook/instance.cfg.in
@@ -78,9 +78,9 @@ parameters-extra = true
 environment =
   IPYTHONDIR=${directory:ipython_dir}
   JUPYTER_CONFIG_DIR=${directory:ipython_dir}
-  LC_ALL=en_US.UTF-8
-  LANG=en_US.UTF-8
-  LANGUAGE=en_US.UTF-8
+  LC_ALL=C.UTF-8
+  LANG=C.UTF-8
+  LANGUAGE=C.UTF-8
 
 [ipython-notebook-config]
 <= dynamic-jinja2-template-base
diff --git a/software/ipython_notebook/software.cfg b/software/ipython_notebook/software.cfg
index 472f0018199f1692381a4953375abde415cda09d..81df4ece74e0e7cc5de51ab141439fa6553448b9 100644
--- a/software/ipython_notebook/software.cfg
+++ b/software/ipython_notebook/software.cfg
@@ -64,7 +64,7 @@ recipe = slapos.recipe.template:jinja2
 template = ${:_profile_base_location_}/instance.cfg.in
 rendered = ${buildout:directory}/template.cfg
 mode = 0644
-md5sum = 5b7141a56eff4104e6b2c4585ee9448e
+md5sum = c9d2c7a3658457b7f43cbbbc38ef247c
 context =
   key bin_directory buildout:bin-directory
   key develop_eggs_directory buildout:develop-eggs-directory