diff --git a/tests/warning/snapshots/issue_6442.snap b/tests/warning/snapshots/issue_6442.snap
new file mode 100644
index 00000000000..75e7888b3cc
--- /dev/null
+++ b/tests/warning/snapshots/issue_6442.snap
@@ -0,0 +1,12 @@
+---
+source: src/test/mod.rs
+---
+error[internal]: line formatted, but exceeded maximum width (maximum: 100 (see `max_width` option), found: 125)
+ --> tests/warning/source/issue_6442.rs:4:4:98
+  |
+4 |     // aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+  |                                                                                                     ^^^^^^^^^^^^^^^^^^^^^^^^^
+  |
+  = note: set `error_on_unformatted = false` to suppress the warning against comments or string literals
+
+warning: rustfmt has failed to format. See previous 1 errors.
diff --git a/tests/warning/source/issue_6442.rs b/tests/warning/source/issue_6442.rs
new file mode 100644
index 00000000000..f3760c97231
--- /dev/null
+++ b/tests/warning/source/issue_6442.rs
@@ -0,0 +1,5 @@
+// rustfmt-hard_tabs: true
+
+fn main() {
+	// aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+}