diff --git a/pyproject.toml b/pyproject.toml
index 586112ae..dc711431 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -43,7 +43,7 @@ doc = [
     "sphinx-autoapi>=1.8,<3.7",
     "sphinx-issues>=1.2,<5.1",
     "sphinx-autodoc-typehints>1.19,<3.2.0",
-    "sphinxcontrib-mermaid>0.7,<1.3.0",
+    "sphinxcontrib-mermaid>0.7,<2.1.0",
 ]
 qa = [ # in local development these are provided globally, here for GHA
     "pre-commit>=2.9,<4.6",  # Allow us to run pre-commit hooks in testing