diff --git a/parsedmarc/__init__.py b/parsedmarc/__init__.py
index 955de32..1f46491 100644
--- a/parsedmarc/__init__.py
+++ b/parsedmarc/__init__.py
@@ -64,8 +64,7 @@ EMAIL_SAMPLE_CONTENT_TYPES = (
     "text/rfc-822-headers",
     "message/rfc822",
     "message/rfc-822",
-    "message/rfc822-headers"
-    "message-rfc-822-headers"
+    "message/rfc822-headersmessage/rfc-822-headers",
 )
 
 IP_ADDRESS_CACHE = ExpiringDict(max_len=10000, max_age_seconds=14400)