diff --git a/example/03-share-key-between-processes.php b/example/03-share-key-between-processes.php
index 12e7b67..861f57a 100644
--- a/example/03-share-key-between-processes.php
+++ b/example/03-share-key-between-processes.php
@@ -12,12 +12,13 @@
 
 $message = new PlainTextMessage("Only the holder of the same key can read this.");
 $cipherText = $message->encrypt($senderKey);
+$ivString = (string)$message->getIv();
 
 echo "Share this key securely: ", $sharedKeyString, PHP_EOL;
 echo "Cipher text to transmit: ", $cipherText, PHP_EOL;
-echo "IV to transmit: ", $message->getIv(), PHP_EOL;
+echo "IV to transmit: ", $ivString, PHP_EOL;
 
-$receivedMessage = new EncryptedMessage($cipherText, $message->getIv());
+$receivedMessage = new EncryptedMessage($cipherText, $ivString);
 $decryptedMessage = $receivedMessage->decrypt($receiverKey);
 
 echo "Decrypted on the receiving side: ", $decryptedMessage, PHP_EOL;
diff --git a/src/Message/AbstractMessage.php b/src/Message/AbstractMessage.php
index 25933e4..36eb62f 100644
--- a/src/Message/AbstractMessage.php
+++ b/src/Message/AbstractMessage.php
@@ -1,6 +1,7 @@
 <?php
 namespace GT\Cipher\Message;
 
+use GT\Cipher\CipherException;
 use GT\Cipher\InitVector;
 use Stringable;
 
@@ -9,8 +10,17 @@ abstract class AbstractMessage implements Stringable {
 
 	public function __construct(
 		protected string $data,
-		?InitVector $iv = null,
+		null|string|InitVector $iv = null,
 	) {
+		if(is_string($iv)) {
+			$decodedIv = base64_decode($iv, true);
+			if($decodedIv === false) {
+				throw new CipherException("IV must be a valid base64 string");
+			}
+
+			$iv = (new InitVector())->withBytes($decodedIv);
+		}
+
 		$this->iv = $iv ?? new InitVector();
 	}
 
diff --git a/test/phpunit/Message/EncryptedMessageTest.php b/test/phpunit/Message/EncryptedMessageTest.php
index 8b29d4e..ba1092d 100644
--- a/test/phpunit/Message/EncryptedMessageTest.php
+++ b/test/phpunit/Message/EncryptedMessageTest.php
@@ -13,6 +13,13 @@ public function testToString():void {
 		self::assertSame("0000", (string)$sut);
 	}
 
+	public function testConstruct_withBase64IvString():void {
+		$ivBytes = base64_decode("8Zf3DaE343vn3LLDiyTlFCS6iFP4RVMw");
+		$sut = new EncryptedMessage("0000", base64_encode($ivBytes));
+
+		self::assertSame($ivBytes, $sut->getIv()->getBytes());
+	}
+
 	/** @noinspection SpellCheckingInspection */
 	public function testDecrypt():void {
 		$iv = self::createMock(InitVector::class);
@@ -55,4 +62,10 @@ public function testDecrypt_wrapsSodiumFailure():void {
 		self::expectException(DecryptionFailureException::class);
 		$sut->decrypt($key);
 	}
+
+	public function testConstruct_invalidBase64IvString():void {
+		self::expectException(\GT\Cipher\CipherException::class);
+		self::expectExceptionMessage("IV must be a valid base64 string");
+		new EncryptedMessage("0000", "%%%");
+	}
 }