diff --git a/schwab_sort.h b/schwab_sort.h
index d7a2130..fa745d3 100644
--- a/schwab_sort.h
+++ b/schwab_sort.h
@@ -114,7 +114,7 @@ inline void sch_insertion_sort(uint32_t *arr, int low, int high) {
 	/* Dual heapsort5 probably helps insertion speed */
 	/* This is sane, because insertion benefits from */
 	/* data being "basically nearly sorted" as input */
-	if(high + 1 - low > 10) {
+	if(high - low > 10) {
 		sch_hsort5(&arr[0]);
 		sch_hsort5(&arr[5]);
 	}