diff --git a/message-types/draw-msg.sml b/message-types/draw-msg.sml
index 793caef..af56cf1 100644
--- a/message-types/draw-msg.sml
+++ b/message-types/draw-msg.sml
@@ -1,13 +1,4 @@
-signature DRAW_MSG =
-sig
-  datatype t =
-    REDRAW_TEXT of Real32.real vector
-  | REDRAW_CURSOR of Real32.real vector
-  | REDRAW_BG of Real32.real vector
-  | YANK of string
-end
-
-structure DrawMsg :> DRAW_MSG =
+structure DrawMsg =
 struct
   datatype t =
     REDRAW_TEXT of Real32.real vector
diff --git a/message-types/input-msg.sml b/message-types/input-msg.sml
index 7818351..a9690b8 100644
--- a/message-types/input-msg.sml
+++ b/message-types/input-msg.sml
@@ -1,7 +1,2 @@
-signature INPUT_MSG =
-sig
-  datatype t = CHAR_EVENT of char | KEY_ESC | RESIZE_EVENT of int * int
-end
-
-structure InputMsg :> INPUT_MSG =
+structure InputMsg =
 struct datatype t = CHAR_EVENT of char | KEY_ESC | RESIZE_EVENT of int * int end
diff --git a/message-types/mailbox-type.sml b/message-types/mailbox-type.sml
index 4bab026..c7f5749 100644
--- a/message-types/mailbox-type.sml
+++ b/message-types/mailbox-type.sml
@@ -1,7 +1 @@
-signature MAILBOX_TYPE =
-sig
-  datatype t = DRAW of DrawMsg.t
-end
-
-structure MailboxType :> MAILBOX_TYPE =
-struct datatype t = DRAW of DrawMsg.t end
+structure MailboxType = struct datatype t = DRAW of DrawMsg.t end