diff --git a/tox.ini b/tox.ini
index 8a286a8c86..646dabea01 100644
--- a/tox.ini
+++ b/tox.ini
@@ -280,7 +280,7 @@ skipsdist = True
 skip_install = True
 deps =
     tomte[docs]==0.2.13
-commands = pip3 install git+https://github.com/pugong/mkdocs-mermaid-plugin.git#egg=mkdocs-mermaid-plugin
+commands = pip3 install git+https://github.com/pugong/mkdocs-mermaid-plugin.git@abf1439#egg=mkdocs-mermaid-plugin
            mkdocs build --clean
 
 [testenv:docs-serve]
@@ -288,7 +288,7 @@ skipsdist = True
 skip_install = True
 deps =
     tomte[docs]==0.2.13
-commands = pip3 install git+https://github.com/pugong/mkdocs-mermaid-plugin.git#egg=mkdocs-mermaid-plugin
+commands = pip3 install git+https://github.com/pugong/mkdocs-mermaid-plugin.git@abf1439#egg=mkdocs-mermaid-plugin
            mkdocs build --clean
            python -c 'print("###### Starting local server. Press Control+C to stop server ######")'
            mkdocs serve -a localhost:8080