diff --git a/src/xdiff/xemit.c b/src/xdiff/xemit.c
index a0078f9..b578e7a 100644
--- a/src/xdiff/xemit.c
+++ b/src/xdiff/xemit.c
@@ -31,7 +31,7 @@
 
 
 static int xdl_emit_record(xdfile_t *xdf, long ri, char const *pre, xdemitcb_t *ecb) {
-	long size, psize = strlen(pre);
+	long size, psize = (long)strlen(pre);
 	char const *rec;
 
 	size = xdl_get_rec(xdf, ri, &rec);