diff --git a/src/handler/get_wallet_address.c b/src/handler/get_wallet_address.c
index 93dc7c648..752ef471d 100644
--- a/src/handler/get_wallet_address.c
+++ b/src/handler/get_wallet_address.c
@@ -93,6 +93,10 @@ void handler_get_wallet_address(dispatcher_context_t *dc, uint8_t protocol_versi
         SEND_SW(dc, SW_WRONG_DATA_LENGTH);
         return;
     }
+    if (address_index >= BIP32_FIRST_HARDENED_CHILD) {
+        SEND_SW(dc, SW_INCORRECT_DATA);  // it must be unhardened
+        return;
+    }
 
     {
         uint8_t serialized_wallet_policy[MAX_WALLET_POLICY_SERIALIZED_LENGTH];
diff --git a/tests/test_get_wallet_address.py b/tests/test_get_wallet_address.py
index 008e0cb50..526637cb8 100644
--- a/tests/test_get_wallet_address.py
+++ b/tests/test_get_wallet_address.py
@@ -231,3 +231,26 @@ def test_get_wallet_address_tr_script_sortedmulti(client: Client):
 
     res = client.get_wallet_address(wallet, wallet_hmac, 0, 0, False)
     assert res == "tb1pdzk72dnvz3246474p4m5a97u43h6ykt2qcjrrhk6y0fkg8hx2mvswwgvv7"
+
+
+def test_get_wallet_address_large_addr_index(client: Client):
+    # 2**31 - 1 is the largest index allowed, per BIP-32
+
+    wallet = MultisigWallet(
+        name="Cold storage",
+        address_type=AddressType.WIT,
+        threshold=2,
+        keys_info=[
+            "[76223a6e/48'/1'/0'/2']tpubDE7NQymr4AFtewpAsWtnreyq9ghkzQBXpCZjWLFVRAvnbf7vya2eMTvT2fPapNqL8SuVvLQdbUbMfWLVDCZKnsEBqp6UK93QEzL8Ck23AwF",
+            "[f5acc2fd/48'/1'/0'/2']tpubDFAqEGNyad35aBCKUAXbQGDjdVhNueno5ZZVEn3sQbW5ci457gLR7HyTmHBg93oourBssgUxuWz1jX5uhc1qaqFo9VsybY1J5FuedLfm4dK",
+        ],
+    )
+    wallet_hmac = bytes.fromhex(
+        "d7c7a60b4ab4a14c1bf8901ba627d72140b2fb907f2b4e35d2e693bce9fbb371"
+    )
+
+    client.get_wallet_address(wallet, wallet_hmac, 0, 2**31 - 1, False)
+
+    # too large address_index, not allowed for an unhardened step
+    with pytest.raises(IncorrectDataError):
+        client.get_wallet_address(wallet, wallet_hmac, 0, 2**31, False)