diff --git a/4.shellSort.md b/4.shellSort.md
index 187ac0e..cfa59f5 100644
--- a/4.shellSort.md
+++ b/4.shellSort.md
@@ -99,7 +99,7 @@ public class ShellSort implements IArraySort {
         int[] arr = Arrays.copyOf(sourceArray, sourceArray.length);
 
         int gap = 1;
-        while (gap < arr.length) {
+        while (gap < arr.length/3) {
             gap = gap * 3 + 1;
         }