diff --git a/tests/journal/amounts-and-commodities.test b/tests/journal/amounts-and-commodities.test
index 3f5c04c3b..bb8dce941 100644
--- a/tests/journal/amounts-and-commodities.test
+++ b/tests/journal/amounts-and-commodities.test
@@ -150,3 +150,16 @@ $ hledger -f- print
 
 $ hledger -f- print
 > //    # any stdout, no stderr, 0 exit code
+
+# 13. Example of surprising decimal mark parsing behaviour.
+# Without a commodity declaration, these amounts are parsed as 10 and 10000.
+# <
+# 2000/1/1
+#     a                $-10,000
+#     b                 $10,000.00
+#
+# $ hledger -f- print
+# could not balance this transaction (real postings are off by $9,990,000)
+# 2000/01/01
+#     a        $-10,000
+#     b     $10,000,000
\ No newline at end of file