diff --git a/.markdown-lint.yml b/.markdown-lint.yml
index 14ed29b4..a7676c83 100644
--- a/.markdown-lint.yml
+++ b/.markdown-lint.yml
@@ -30,6 +30,10 @@
 # Rules by tags #
 #################
 
+# First line in a file being a top-level heading collides with starting
+# each file with a copyright statement.
+first-line-h1: false
+
 # MD013/line-length - Line length
 line-length:
     line_length: 900 # Arbitrary length to catch the worst. Setting this to 120 affects 500 lines
diff --git a/tox.ini b/tox.ini
index c89a9d0d..f8fec588 100644
--- a/tox.ini
+++ b/tox.ini
@@ -79,4 +79,4 @@ changedir = {toxinidir}
 allowlist_externals =
     npx
 commands =
-    npx markdownlint-cli -c .markdown-lint.yml *.md **/*.md
+    npx markdownlint-cli@v0.34.0 -c .markdown-lint.yml *.md **/*.md