diff --git a/docs/source/installation/images/k2-v1.9-blueviolet.svg b/docs/source/installation/images/k2-v1.9-blueviolet.svg
new file mode 100644
index 000000000..5a207b370
--- /dev/null
+++ b/docs/source/installation/images/k2-v1.9-blueviolet.svg
@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="58" height="20" role="img" aria-label="k2: v1.9"><title>k2: v1.9</title><linearGradient id="s" x2="0" y2="100%"><stop offset="0" stop-color="#bbb" stop-opacity=".1"/><stop offset="1" stop-opacity=".1"/></linearGradient><clipPath id="r"><rect width="58" height="20" rx="3" fill="#fff"/></clipPath><g clip-path="url(#r)"><rect width="23" height="20" fill="#555"/><rect x="23" width="35" height="20" fill="blueviolet"/><rect width="58" height="20" fill="url(#s)"/></g><g fill="#fff" text-anchor="middle" font-family="Verdana,Geneva,DejaVu Sans,sans-serif" text-rendering="geometricPrecision" font-size="110"><text aria-hidden="true" x="125" y="150" fill="#010101" fill-opacity=".3" transform="scale(.1)" textLength="130">k2</text><text x="125" y="140" transform="scale(.1)" fill="#fff" textLength="130">k2</text><text aria-hidden="true" x="395" y="150" fill="#010101" fill-opacity=".3" transform="scale(.1)" textLength="250">v1.9</text><text x="395" y="140" transform="scale(.1)" fill="#fff" textLength="250">v1.9</text></g></svg>
\ No newline at end of file
diff --git a/docs/source/installation/index.rst b/docs/source/installation/index.rst
index 588ec13ec..e269cae57 100644
--- a/docs/source/installation/index.rst
+++ b/docs/source/installation/index.rst
@@ -1,4 +1,4 @@
-.. _install icefall:
+9. _install icefall:
 
 Installation
 ============
@@ -21,7 +21,7 @@ Installation
 .. |torch_versions| image:: ./images/torch-1.6.0_1.7.0_1.7.1_1.8.0_1.8.1_1.9.0-green.svg
   :alt: Supported PyTorch versions
 
-.. |k2_versions| image:: ./images/k2-v-1.7.svg
+.. |k2_versions| image:: ./images/k2-v1.9-blueviolet.svg
   :alt: Supported k2 versions
 
 ``icefall`` depends on `k2 <https://github.com/k2-fsa/k2>`_ and
@@ -40,7 +40,7 @@ to install ``k2``.
 
 .. CAUTION::
 
-  You need to install ``k2`` with a version at least **v1.7**.
+  You need to install ``k2`` with a version at least **v1.9**.
 
 .. HINT::