diff --git a/pyproject.toml b/pyproject.toml
index 1180ce3..fc5e83c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -11,7 +11,7 @@ dependencies = [
     # Zensical replaces mkdocs + mkdocs-material (built by the same team).
     # Pinned to a known-good alpha; bump deliberately.
     "zensical==0.0.41",
-    "pymdown-extensions>=10.17.1,<12.0",
+    "pymdown-extensions>=12.1,<12.2",
     # Note: git-revision-date-localized and htmlproofer plugins are not yet
     # supported by Zensical (alpha, Phase 1). Link-checking is handled by the
     # `links.yml` workflow via lychee.
diff --git a/uv.lock b/uv.lock
index 6045611..0b05bc3 100644
--- a/uv.lock
+++ b/uv.lock
@@ -18,7 +18,7 @@ dev = [
 
 [package.metadata]
 requires-dist = [
-    { name = "pymdown-extensions", specifier = ">=10.17.1,<12.0" },
+    { name = "pymdown-extensions", specifier = ">=12.1,<12.2" },
     { name = "zensical", specifier = "==0.0.41" },
 ]
 
@@ -220,15 +220,15 @@ wheels = [
 
 [[package]]
 name = "pymdown-extensions"
-version = "10.21.3"
+version = "12.1"
 source = { registry = "https://pypi.org/simple" }
 dependencies = [
     { name = "markdown" },
     { name = "pyyaml" },
 ]
-sdist = { url = "https://files.pythonhosted.org/packages/9e/26/d1015444da4d952a1ca487a236b522eb979766f0295a0bd0c5fc089989a9/pymdown_extensions-10.21.3.tar.gz", hash = "sha256:72cfcf55f07aea0d4af2c4f11dd4e52466ddfb1bb819673146398e0bd3a77354", size = 854140, upload-time = "2026-05-13T12:57:32.267Z" }
+sdist = { url = "https://files.pythonhosted.org/packages/2a/94/858e0163cb4d83d6d8234018a01792c749a56daee41794cac7d6c46661e8/pymdown_extensions-12.1.tar.gz", hash = "sha256:fdb8f47f5d7fd069d10ef2a7d8908e613d7865ff0419d544a0ffd3984e884f11", size = 868245, upload-time = "2026-09-23T00:08:42Z" }
 wheels = [
-    { url = "https://files.pythonhosted.org/packages/7e/85/545a951eecc270fcd688288c600017e2050a1aacb56c711d208586d3e470/pymdown_extensions-10.21.3-py3-none-any.whl", hash = "sha256:d7a5d08014fc571e80ca21dd6f854e31f94c489800350564d55d15b3c41e76b6", size = 269002, upload-time = "2026-05-13T12:57:30.296Z" },
+    { url = "https://files.pythonhosted.org/packages/36/d1/98313da89960a604402266a115311b510254900ff1295ea426403f9423cc/pymdown_extensions-12.1-py3-none-any.whl", hash = "sha256:4a254b771acfcddc6c110a7f4590d818f1f849e2d5aacf69b4b07c8dd2a9700d", size = 277069, upload-time = "2026-09-23T00:08:40.069Z" },
 ]
 
 [[package]]