diff --git a/simple-algorithms/longest-substring/build.gradle b/simple-algorithms/longest-substring/build.gradle
index e81e635..e2b9b60 100644
--- a/simple-algorithms/longest-substring/build.gradle
+++ b/simple-algorithms/longest-substring/build.gradle
@@ -2,7 +2,7 @@ plugins {
     id 'java'
 }
 
-def junitVersion = '5.9.3'
+def junitVersion = '5.10.2'
 
 group 'com.josdem.kata'
 version '1.0-SNAPSHOT'
diff --git a/simple-algorithms/longest-substring/src/main/java/com/josdem/kata/LongestSubstring.java b/simple-algorithms/longest-substring/src/main/java/com/josdem/kata/LongestSubstring.java
index 0645614..5881066 100644
--- a/simple-algorithms/longest-substring/src/main/java/com/josdem/kata/LongestSubstring.java
+++ b/simple-algorithms/longest-substring/src/main/java/com/josdem/kata/LongestSubstring.java
@@ -7,6 +7,6 @@ public class LongestSubstring {
     public int reduce(String data) {
         List<String> substrings =
                 Arrays.stream(data.split("")).distinct().toList();
-        return substrings.size() > 0 ? substrings.size() : 1;
+        return !substrings.isEmpty() ? substrings.size() : 1;
     }
 }