diff --git a/src/apps/wallet/sign_tx/omni.py b/src/apps/wallet/sign_tx/omni.py
index 0b6f63d7ae..a475d2826c 100644
--- a/src/apps/wallet/sign_tx/omni.py
+++ b/src/apps/wallet/sign_tx/omni.py
@@ -6,7 +6,7 @@ currencies = {1: "OMNI", 2: "tOMNI", 3: "MAID", 31: "USDT"}
 
 
 def is_valid(data: bytes) -> bool:
-    return data[:4] == b"omni"
+    return len(data) >= 8 and data[:4] == b"omni"
 
 
 def parse(data: bytes) -> bool:
diff --git a/tests/test_apps.wallet.signtx.omni.py b/tests/test_apps.wallet.signtx.omni.py
index 4d1c26ece9..119599ef0c 100644
--- a/tests/test_apps.wallet.signtx.omni.py
+++ b/tests/test_apps.wallet.signtx.omni.py
@@ -6,7 +6,9 @@ class TestSignTxOmni(unittest.TestCase):
 
     def test_is_valid(self):
         VECTORS = {
-             "6f6d6e69000000000000001f000000002b752ee0": True,
+             "6f6d6e69": False,
+             "6f6d6e69000000": False,
+             "6f6d6e6900000000": True,
              "6f6d6e69000000000000001f0000000020c85580": True,
              "0f6d6e69000000000000001f0000000020c85580": False,
              "6f6d6e69000000000000001f0000000020c8558000": True,