diff --git a/src/structs.h b/src/structs.h
index da4ffb8..ad03cd4 100644
--- a/src/structs.h
+++ b/src/structs.h
@@ -1972,9 +1972,11 @@
      * b_fname is the same as b_sfname, unless ":cd" has been done,
      *		then it is the same as b_ffname (NULL for no name).
      */
-    char_u	*b_ffname;	/* full path file name */
-    char_u	*b_sfname;	/* short file name */
-    char_u	*b_fname;	/* current file name */
+    char_u	*b_ffname;	// full path file name, allocated
+    char_u	*b_sfname;	// short file name, allocated, may be equal to
+				// b_ffname
+    char_u	*b_fname;	// current file name, points to b_ffname or
+				// b_sfname
 
 #ifdef UNIX
     int		b_dev_valid;	/* TRUE when b_dev has a valid number */