diff --git a/usr.bin/diff/diffreg.c b/usr.bin/diff/diffreg.c
--- a/usr.bin/diff/diffreg.c
+++ b/usr.bin/diff/diffreg.c
@@ -1345,7 +1345,7 @@
 readhash(FILE *f, int flags)
 {
 	int i, t, space;
-	int sum;
+	unsigned sum;
 
 	sum = 1;
 	space = 0;