diff --git a/HISTORY.rst b/HISTORY.rst
index 312a98e3c..edb5cec04 100644
--- a/HISTORY.rst
+++ b/HISTORY.rst
@@ -3,6 +3,13 @@
 Release History
 ---------------
 
+1.2.1 (2019-07-20)
+++++++++++++++++++++++
+
+**Improvements**
+
+- Documented how to use Jupytext with JupyterLab 0.35 (#299)
+
 1.2.0 (2019-07-18)
 ++++++++++++++++++++++
 
diff --git a/README.md b/README.md
index 0b301e9cf..7e42b14b4 100755
--- a/README.md
+++ b/README.md
@@ -89,6 +89,11 @@ The Jupytext extension for JupyterLab is bundled with Jupytext. Installing Jupyt
 jupyter lab build
 ```
 
+The version of the extension that is shipped with Jupytext requires JupyterLab 1.0. If you prefer to continue using JupyterLab in version 0.35, you should install the version 0.19 of the extension:
+```
+jupyter labextension install jupyterlab-jupytext@0.19
+``` 
+
 ## Using Jupytext
 
 ### Paired notebooks in the Jupyter Server
diff --git a/docs/install.md b/docs/install.md
index 46d379767..7fc8b5fb8 100644
--- a/docs/install.md
+++ b/docs/install.md
@@ -53,3 +53,8 @@ The Jupytext extension for JupyterLab is bundled with Jupytext. Installing Jupyt
 ```
 jupyter lab build
 ```
+
+The version of the extension that is shipped with Jupytext requires JupyterLab 1.0. If you prefer to continue using JupyterLab in version 0.35, you should install the version 0.19 of the extension:
+```
+jupyter labextension install jupyterlab-jupytext@0.19
+```