diff --git a/run/john.conf b/run/john.conf
index 341940f8ce..4835d27787 100644
--- a/run/john.conf
+++ b/run/john.conf
@@ -3978,7 +3978,7 @@ void init()
 	max_length = 10;
 
 	/* Prepare a 12-bit count leading zero table */
-	int i; i = -1;
+	int i; i = 0;
 	while (i++ < 12) {
 		int j; j = 0;
 		while (j < 0x1000)
@@ -4025,7 +4025,7 @@ void next()
 			k = id[i];
 			int mask; mask = prev_unseen;
 			while (k--)
-				mask &= mask - 1;
+				mask = mask & --mask; /* Would be UB in C /
 			/* Count how many total indices we skipped */
 			if ((j = clz[mask & 0xfff]) == 12) {
 				while ((k = clz[(mask >>= 12) & 0xfff]) == 12)