diff --git a/tests/ui/frontmatter/fence-too-many-dashes.rs b/tests/ui/frontmatter/fence-too-many-dashes.rs
new file mode 100644
index 000000000000..2246a14044fc
--- /dev/null
+++ b/tests/ui/frontmatter/fence-too-many-dashes.rs
@@ -0,0 +1,12 @@
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+// ignore-tidy-linelength
+[dependencies]
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+
+#![feature(frontmatter)]
+
+//@ check-pass
+
+// check that we limit fence lengths
+
+fn main() {}