diff --git a/MSGViewer/src/test/java/net/sourceforge/MSGViewer/factory/mbox/JavaMailParserTest.java b/MSGViewer/src/test/java/net/sourceforge/MSGViewer/factory/mbox/JavaMailParserTest.java
index 3423c16a..34e61fbe 100644
--- a/MSGViewer/src/test/java/net/sourceforge/MSGViewer/factory/mbox/JavaMailParserTest.java
+++ b/MSGViewer/src/test/java/net/sourceforge/MSGViewer/factory/mbox/JavaMailParserTest.java
@@ -1,12 +1,17 @@
 package net.sourceforge.MSGViewer.factory.mbox;
 
 import com.auxilii.msgparser.Message;
+import com.auxilii.msgparser.attachment.Attachment;
+import com.auxilii.msgparser.attachment.FileAttachment;
+import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.CsvSource;
 
 import java.net.URI;
 import java.nio.file.Path;
+import java.util.List;
 
+import static org.assertj.core.api.Assertions.assertThat;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
 class JavaMailParserTest {
@@ -20,4 +25,18 @@ void should_parse_charset(String resource, String expected) throws Exception {
         String bodyText = message.getBodyText();
         assertTrue(bodyText.contains(expected));
     }
+
+    @Test
+    void should_throw() throws Exception {
+        URI uri = JavaMailParserTest.class.getResource("/unnamed-attachment.eml").toURI();
+        Path file = Path.of(uri);
+        JavaMailParser sut = new JavaMailParser(file);
+        Message message = sut.parse();
+        List<Attachment> attachments = message.getAttachments();
+        assertThat(attachments)
+                .element(0)
+                .isInstanceOf(FileAttachment.class)
+                .extracting(attachment -> ((FileAttachment) attachment).getLongFilename())
+                .isEqualTo("unknown");
+    }
 }
diff --git a/MSGViewer/src/test/resources/unnamed-attachment.eml b/MSGViewer/src/test/resources/unnamed-attachment.eml
new file mode 100644
index 00000000..f2463d37
--- /dev/null
+++ b/MSGViewer/src/test/resources/unnamed-attachment.eml
@@ -0,0 +1,86 @@
+Content-Transfer-Encoding: quoted-printable
+To: bar <example@gmail.com>
+From: Foo <foo@example.com>
+Subject: test
+Content-Type: image/gif
+Content-Disposition: inline
+Content-Transfer-Encoding: base64
+
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\ No newline at end of file