diff --git a/editors/diff.c b/editors/diff.c
index 64ad651..0e96c84 100644
--- a/editors/diff.c
+++ b/editors/diff.c
@@ -1189,7 +1189,7 @@
 		recursive_action(path, ACTION_RECURSE|ACTION_FOLLOWLINKS,
 					add_to_dirlist, /* file_action */
 					NULL, /* dir_action */
-					(void*)(strlen(path) + 1),
+					(void*)(ptrdiff_t)(strlen(path) + 1),
 					0);
 	} else {
 		DIR *dp;