diff --git a/xdiff/xprepare.c b/xdiff/xprepare.c
index 48fb5ce6fe..386668a92d 100644
--- a/xdiff/xprepare.c
+++ b/xdiff/xprepare.c
@@ -197,8 +197,8 @@ void xdl_free_env(xdfenv_t *xe) {
 }
 
 
-static bool xdl_clean_mmatch(uint8_t const *action, long i, long s, long e) {
-	long r, rdis0, rpdis0, rdis1, rpdis1;
+static bool xdl_clean_mmatch(uint8_t const *action, ptrdiff_t i, ptrdiff_t s, ptrdiff_t e) {
+	ptrdiff_t r, rdis0, rpdis0, rdis1, rpdis1;
 
 	/*
 	 * Limits the window that is examined during the similar-lines
@@ -268,7 +268,7 @@ static bool xdl_clean_mmatch(uint8_t const *action, long i, long s, long e) {
  * might be potentially discarded if they appear in a run of discardable.
  */
 static int xdl_cleanup_records(xdlclassifier_t *cf, xdfile_t *xdf1, xdfile_t *xdf2) {
-	long i, nm, mlim;
+	ptrdiff_t i, nm, mlim;
 	xdlclass_t *rcrec;
 	uint8_t *action1 = NULL, *action2 = NULL;
 	bool need_min = !!(cf->flags & XDF_NEED_MINIMAL);