diff --git a/src/bin/mail_utils/mail2mbox.rdef b/src/bin/mail_utils/mail2mbox.rdef
index c99fcde8d8..8edd6d9075 100644
--- a/src/bin/mail_utils/mail2mbox.rdef
+++ b/src/bin/mail_utils/mail2mbox.rdef
@@ -3,7 +3,7 @@
 
 resource app_flags B_SINGLE_LAUNCH | B_ARGV_ONLY;
 
-resource app_signature "application/x-vnd.agmsmith.bemailtombox";
+resource app_signature "application/x-vnd.Haiku-mail2mbox";
 
 resource app_version {
 	major  = 1,
diff --git a/src/bin/mail_utils/mbox2mail.rdef b/src/bin/mail_utils/mbox2mail.rdef
index 69eaea2f3d..1e94af1c4b 100644
--- a/src/bin/mail_utils/mbox2mail.rdef
+++ b/src/bin/mail_utils/mbox2mail.rdef
@@ -3,7 +3,7 @@
 
 resource app_flags B_SINGLE_LAUNCH | B_ARGV_ONLY;
 
-resource app_signature "application/x-vnd.agmsmith.mboxtobemail";
+resource app_signature "application/x-vnd.Haiku-mbox2mail";
 
 resource app_version {
 	major  = 1,