diff --git a/src/kits/mail/HaikuMailFormatFilter.cpp b/src/kits/mail/HaikuMailFormatFilter.cpp
index a5590a6042..9bb086757f 100644
--- a/src/kits/mail/HaikuMailFormatFilter.cpp
+++ b/src/kits/mail/HaikuMailFormatFilter.cpp
@@ -169,7 +169,7 @@ HaikuMailFormatFilter::HeaderFetched(const entry_ref& ref, BFile* file)
 	}
 
 	BNodeInfo info(file);
-	info.SetType("text/x-partial-email");
+	info.SetType(B_PARTIAL_MAIL_TYPE);
 }