diff --git a/android/app/src/androidTest/java/com/trustwallet/core/app/blockchains/ethereum/TestEthereumMessageSigner.kt b/android/app/src/androidTest/java/com/trustwallet/core/app/blockchains/ethereum/TestEthereumMessageSigner.kt
index 6b86f698769..6245751d124 100644
--- a/android/app/src/androidTest/java/com/trustwallet/core/app/blockchains/ethereum/TestEthereumMessageSigner.kt
+++ b/android/app/src/androidTest/java/com/trustwallet/core/app/blockchains/ethereum/TestEthereumMessageSigner.kt
@@ -36,6 +36,17 @@ class TestEthereumMessageSigner {
         assertTrue(EthereumMessageSigner.verifyMessage(publicKey, msg, signature))
     }
 
+    @Test
+    fun testEthereumSignAndVerifyMessageLegacyHex() {
+        val data = Numeric.hexStringToByteArray("9066aa168c379a403becb235c15e7129c133c244e56a757ab07bc369288bcab0")
+        val privateKey = PrivateKey(data)
+        val publicKey = privateKey.getPublicKey(CoinType.ETHEREUM)
+        val msg = "0xc0a96273d5c3fbe4d4000491f08daef9c17f88df846c1d6f57eb5f33c1fbd035"
+        val signature = EthereumMessageSigner.signMessage(privateKey, msg)
+        assertEquals(signature, "b18a666ad08bf9bfcd39920b26b5a5d1486b67b45119810b3c7bda22e41e5c4c1bfbe0c932f6c14df4947a18ba310831a37b7307d724a3ac2a4935b99d7075141b");
+        assertTrue(EthereumMessageSigner.verifyMessage(publicKey, msg, signature))
+    }
+
     @Test
     fun testEthereumSignAndVerifyMessage712Legacy() {
         val data = Numeric.hexStringToByteArray("03a9ca895dca1623c7dfd69693f7b4111f5d819d2e145536e0b03c136025a25d")
diff --git a/rust/tw_evm/src/message/eip191.rs b/rust/tw_evm/src/message/eip191.rs
index cb2bd715d8e..ed532f6cc2e 100644
--- a/rust/tw_evm/src/message/eip191.rs
+++ b/rust/tw_evm/src/message/eip191.rs
@@ -3,6 +3,7 @@
 // Copyright © 2017 Trust Wallet.
 
 use crate::message::{EthMessage, MessageSigningResult};
+use tw_encoding::hex;
 use tw_hash::sha3::keccak256;
 use tw_hash::H256;
 
@@ -27,8 +28,18 @@ impl Eip191Message {
 
         data.push(ETHEREUM_PREFIX);
         data.extend_from_slice(ETHEREUM_MESSAGE_PREFIX.as_bytes());
-        data.extend_from_slice(self.user_message.len().to_string().as_bytes());
-        data.extend_from_slice(self.user_message.as_bytes());
+
+        let mut do_extend = |bytes: &[u8]| {
+            data.extend_from_slice(bytes.len().to_string().as_bytes());
+            data.extend_from_slice(bytes);
+        };
+
+        match hex::decode(&self.user_message) {
+            // Handle the message as hex-encoded.
+            Ok(raw_msg) => do_extend(&raw_msg),
+            // Handle as a regular string.
+            Err(_) => do_extend(self.user_message.as_bytes()),
+        }
 
         data
     }
diff --git a/rust/tw_evm/tests/message_signer.rs b/rust/tw_evm/tests/message_signer.rs
index e09efef30fc..447e48df6db 100644
--- a/rust/tw_evm/tests/message_signer.rs
+++ b/rust/tw_evm/tests/message_signer.rs
@@ -127,6 +127,19 @@ fn test_message_signer_sign_verify_legacy() {
     });
 }
 
+/// https://github.com/trustwallet/wallet-core/issues/3831
+#[test]
+fn test_message_signer_sign_verify_legacy_hex() {
+    test_message_signer_sign_verify(SignVerifyTestInput {
+        // 0x9d1d97adfcd324bbd603d3872bd78e04098510b1
+        private_key: "9066aa168c379a403becb235c15e7129c133c244e56a757ab07bc369288bcab0",
+        msg: "0xc0a96273d5c3fbe4d4000491f08daef9c17f88df846c1d6f57eb5f33c1fbd035",
+        msg_type: Proto::MessageType::MessageType_legacy,
+        chain_id: None,
+        signature: "b18a666ad08bf9bfcd39920b26b5a5d1486b67b45119810b3c7bda22e41e5c4c1bfbe0c932f6c14df4947a18ba310831a37b7307d724a3ac2a4935b99d7075141b",
+    });
+}
+
 #[test]
 fn test_message_signer_sign_verify_eip155() {
     test_message_signer_sign_verify(SignVerifyTestInput {