diff --git a/pqcli/lingo.py b/pqcli/lingo.py
index 3573bd5..43461d3 100644
--- a/pqcli/lingo.py
+++ b/pqcli/lingo.py
@@ -97,7 +97,7 @@ def plural(subject: str) -> str:
 
 def indefinite(subject: str, qty: int) -> str:
     if qty == 1:
-        if subject.startswith(tuple("AEIOU?aeiou?")):
+        if subject.startswith(tuple("AEIOUÜaeiouü")):
             return "an " + subject
         return "a " + subject
     return str(qty) + " " + plural(subject)
diff --git a/tests/test_lingo.py b/tests/test_lingo.py
new file mode 100644
index 0000000..4d96f27
--- /dev/null
+++ b/tests/test_lingo.py
@@ -0,0 +1,9 @@
+from pqcli.lingo import indefinite, to_roman
+
+
+def test_indefinite_article() -> None:
+    assert indefinite("Orc", 1) == "an Orc"
+    assert indefinite("Ürn", 1) == "an Ürn"
+    assert indefinite("über-Orc", 1) == "an über-Orc"
+    assert indefinite("?", 1) == "a ?"
+    assert indefinite("Rat", 1) == "a Rat"