diff --git a/src/validators/iban.py b/src/validators/iban.py
index ff39cd7..cc6224b 100644
--- a/src/validators/iban.py
+++ b/src/validators/iban.py
@@ -38,7 +38,10 @@ def iban(value: str, /):
         (ValidationError): If `value` is an invalid IBAN code.
     """
     return (
-        (re.match(r"^[a-z]{2}[0-9]{2}[a-z0-9]{11,30}$", value, re.IGNORECASE) and _mod_check(value))
+        (
+            re.match(r"^[a-z]{2}[0-9]{2}[a-z0-9]{11,30}$", value, re.IGNORECASE | re.ASCII)
+            and _mod_check(value)
+        )
         if value
         else False
     )
diff --git a/tests/test_iban.py b/tests/test_iban.py
index 329a20e..16635f3 100644
--- a/tests/test_iban.py
+++ b/tests/test_iban.py
@@ -23,3 +23,9 @@ def test_returns_true_on_valid_lowercase_iban(value: str):
 def test_returns_failed_validation_on_invalid_iban(value: str):
     """Test returns failed validation on invalid iban."""
     assert isinstance(iban(value), ValidationError)
+
+
+@pytest.mark.parametrize("value", ["\u0131T60X0542811101000000123456", "GB82WE\u017fT12345698765432"])
+def test_rejects_non_ascii_case_equivalents(value: str):
+    """Unicode case equivalents must not pass the ASCII IBAN format check."""
+    assert isinstance(iban(value), ValidationError)