diff --git a/src/nano.h b/src/nano.h
index fa38de149eb3e71505f7afe06b054ddad5a943cc..77420221644b85e0c4a54387dad26f90832b6c5a 100644
--- a/src/nano.h
+++ b/src/nano.h
@@ -164,7 +164,7 @@ typedef enum {
 #ifndef DISABLE_WRAPPING
     SPLIT_BEGIN, SPLIT_END,
 #endif
-#ifndef DISABLE_COMMENT
+#ifdef ENABLE_COMMENT
     COMMENT, UNCOMMENT, PREFLIGHT,
 #endif
     JOIN, PASTE, INSERT, ENTER, OTHER
diff --git a/src/proto.h b/src/proto.h
index 1e15d05308ccd3fbe3ddd91b05fabea562ecb9d0..f2246fa7ea5f978568cc0a91ed1eaa1d8a0b6868 100644
--- a/src/proto.h
+++ b/src/proto.h
@@ -540,7 +540,7 @@ RETSIGTYPE cancel_command(int signal);
 bool execute_command(const char *command);
 void discard_until(const undo *thisitem, openfilestruct *thefile);
 void add_undo(undo_type action);
-#ifndef DISABLE_COMMENT
+#ifdef ENABLE_COMMENT
 void update_comment_undo(ssize_t lineno);
 #endif
 void update_undo(undo_type action);