diff --git a/Dockerfile b/Dockerfile
index b9405c8..16dc6b3 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,8 +1,8 @@
-FROM python:3.8.5
+FROM python:3.9.2
 
 RUN apt-get update && \
     apt-get install -y emacs git && \
     apt-get autoclean && \
-    pip install 'Nikola[extras]' && \
+    pip install 'Nikola[extras]==8.1.3' && \
     mkdir -p ~/.emacs.d/.local/straight/build && \
     git clone https://github.com/hniksic/emacs-htmlize.git ~/.emacs.d/.local/straight/build/htmlize