diff --git a/threepass_xbit.h b/threepass_xbit.h
index da05422..2869779 100644
--- a/threepass_xbit.h
+++ b/threepass_xbit.h
@@ -96,11 +96,11 @@ static inline void threepass_xb(uint32_t *a, uint32_t *buf, int n) noexcept {
 	// Bottom digit a->buf
 	// right-to-left to ensure already sorted digits order we keep for iterations
 	#pragma GCC unroll 48
-	for(uint32_t i = n; i > 0; --i) {
+	for(int i = n - 1; i >= 0; --i) {
 		// Prefetch caches
 		//__builtin_prefetch(&a[i-8]);
 		// Get num and its new offset / location
-		auto num = a[i - 1];
+		auto num = a[i];
 		auto bkeyni = (num >> shr3) & mask3;
 		auto offset = --bucket3[bkeyni];
 
@@ -114,11 +114,11 @@ static inline void threepass_xb(uint32_t *a, uint32_t *buf, int n) noexcept {
 	// Mid digit buf->a
 	// right-to-left to ensure already sorted digits order we keep for iterations
 	#pragma GCC unroll 48
-	for(uint32_t i = n; i > 0; --i) {
+	for(int i = n - 1; i >= 0; --i) {
 		// Prefetch caches
 		//__builtin_prefetch(&buf[i-8]);
 		// Get num and its new offset / location
-		auto num = buf[i - 1];
+		auto num = buf[i];
 		auto bkeyni = (num >> shr2) & mask2;
 		auto offset = --bucket2[bkeyni];
 
@@ -132,11 +132,11 @@ static inline void threepass_xb(uint32_t *a, uint32_t *buf, int n) noexcept {
 	// Top digit a->buf
 	// right-to-left to ensure already sorted digits order we keep for iterations
 	#pragma GCC unroll 48
-	for(uint32_t i = n; i > 0; --i) {
+	for(int i = n - 1; i >= 0; --i) {
 		// Prefetch caches
 		// __builtin_prefetch(&a[i-16]);
 		// Get num and its new offset / location
-		auto num = a[i - 1];
+		auto num = a[i];
 		auto bkeyni = (num >> shr1) & mask1;
 		auto offset = --bucket1[bkeyni];