diff --git a/lib/database.cc b/lib/database.cc
index 553c9f82..3ed19772 100644
--- a/lib/database.cc
+++ b/lib/database.cc
@@ -734,6 +734,38 @@ _notmuch_database_get_directory_path (void *ctx,
     return talloc_strdup (ctx, document.get_data ().c_str ());
 }
 
+/* Given a legal 'filename' for the database, (either relative to
+ * database path or absolute with initial components identical to
+ * database path), return a new string (with 'ctx' as the talloc
+ * owner) suitable for use as a direntry term value.
+ */
+notmuch_status_t
+_notmuch_database_filename_to_direntry (void *ctx,
+					notmuch_database_t *notmuch,
+					const char *filename,
+					char **direntry)
+{
+    const char *relative, *directory, *basename;
+    Xapian::docid directory_id;
+    notmuch_status_t status;
+
+    relative = _notmuch_database_relative_path (notmuch, filename);
+
+    status = _notmuch_database_split_path (ctx, relative,
+					   &directory, &basename);
+    if (status)
+	return status;
+
+    status = _notmuch_database_find_directory_id (notmuch, directory,
+						  &directory_id);
+    if (status)
+	return status;
+
+    *direntry = talloc_asprintf (ctx, "%u:%s", directory_id, basename);
+
+    return NOTMUCH_STATUS_SUCCESS;
+}
+
 /* Given a legal 'path' for the database, return the relative path.
  *
  * The return value will be a pointer to the originl path contents,
diff --git a/lib/message.cc b/lib/message.cc
index 7d586903..bd179519 100644
--- a/lib/message.cc
+++ b/lib/message.cc
@@ -393,11 +393,9 @@ notmuch_status_t
 _notmuch_message_add_filename (notmuch_message_t *message,
 			       const char *filename)
 {
-    const char *relative, *directory, *basename;
-    char *term;
-    Xapian::docid directory_id;
     notmuch_status_t status;
     void *local = talloc_new (message);
+    char *direntry;
 
     if (message->filename) {
 	talloc_free (message->filename);
@@ -407,22 +405,13 @@ _notmuch_message_add_filename (notmuch_message_t *message,
     if (filename == NULL)
 	INTERNAL_ERROR ("Message filename cannot be NULL.");
 
-    relative = _notmuch_database_relative_path (message->notmuch, filename);
-
-    status = _notmuch_database_split_path (local, relative,
-					   &directory, &basename);
+    status = _notmuch_database_filename_to_direntry (local,
+						     message->notmuch,
+						     filename, &direntry);
     if (status)
 	return status;
 
-    status = _notmuch_database_find_directory_id (message->notmuch, directory,
-						  &directory_id);
-    if (status)
-	return status;
-
-    term = talloc_asprintf (local, "%s%u:%s",
-			    _find_prefix ("direntry"), directory_id, basename);
-
-    message->doc.add_term (term);
+    _notmuch_message_add_term (message, "direntry", direntry);
 
     talloc_free (local);
 
diff --git a/lib/notmuch-private.h b/lib/notmuch-private.h
index e9712832..cb93c397 100644
--- a/lib/notmuch-private.h
+++ b/lib/notmuch-private.h
@@ -171,6 +171,12 @@ _notmuch_database_get_directory_path (void *ctx,
 				      notmuch_database_t *notmuch,
 				      unsigned int doc_id);
 
+notmuch_status_t
+_notmuch_database_filename_to_direntry (void *ctx,
+					notmuch_database_t *notmuch,
+					const char *filename,
+					char **direntry);
+
 /* thread.cc */
 
 notmuch_thread_t *