diff --git a/client/src/main/java/io/split/client/SplitClientConfig.java b/client/src/main/java/io/split/client/SplitClientConfig.java
index 4677e174d..380d33f3e 100644
--- a/client/src/main/java/io/split/client/SplitClientConfig.java
+++ b/client/src/main/java/io/split/client/SplitClientConfig.java
@@ -934,7 +934,7 @@ public Builder customStorageWrapper(CustomStorageWrapper customStorageWrapper) {
          */
         public Builder flagSetsFilter(List<String> flagSetsFilter) {
             FSValidatorResult fsValidatorResult = cleanup(flagSetsFilter);
-            _flagSetsFilter = new HashSet<>(fsValidatorResult.getFlagSets());
+            _flagSetsFilter = fsValidatorResult.getFlagSets();
             _invalidSets = fsValidatorResult.getInvalidSets();
             return this;
         }
diff --git a/client/src/main/java/io/split/inputValidation/FSValidatorResult.java b/client/src/main/java/io/split/inputValidation/FSValidatorResult.java
index 87149bb5f..3b0bfe3b3 100644
--- a/client/src/main/java/io/split/inputValidation/FSValidatorResult.java
+++ b/client/src/main/java/io/split/inputValidation/FSValidatorResult.java
@@ -1,21 +1,24 @@
 package io.split.inputValidation;
 
-import java.util.List;
+import java.util.HashSet;
+import java.util.LinkedHashSet;
+import java.util.Set;
+import java.util.TreeSet;
 
 public class FSValidatorResult {
-    private final List<String> _flagSets;
+    private final Set<String> _flagSets;
     private final int _invalidSets;
 
-    public FSValidatorResult(List<String> flagSets, Integer invalidSets) {
+    public FSValidatorResult(TreeSet<String> flagSets, Integer invalidSets) {
         _flagSets = flagSets;
         _invalidSets = invalidSets;
     }
 
-    public List<String> getFlagSets() {
-        return _flagSets;
+    public HashSet<String> getFlagSets() {
+        return new LinkedHashSet<>(_flagSets);
     }
 
     public int getInvalidSets() {
         return _invalidSets;
     }
-}
+}
\ No newline at end of file
diff --git a/client/src/main/java/io/split/inputValidation/FlagSetsValidator.java b/client/src/main/java/io/split/inputValidation/FlagSetsValidator.java
index 8851c5884..77344f41c 100644
--- a/client/src/main/java/io/split/inputValidation/FlagSetsValidator.java
+++ b/client/src/main/java/io/split/inputValidation/FlagSetsValidator.java
@@ -3,7 +3,6 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.List;
 import java.util.TreeSet;
@@ -19,10 +18,10 @@ private FlagSetsValidator() {
     }
 
     public static FSValidatorResult cleanup(List<String> flagSets) {
+        TreeSet<String> cleanFlagSets = new TreeSet<>();
         if (flagSets == null || flagSets.isEmpty()) {
-            return new FSValidatorResult(new ArrayList<>(), 0);
+            return new FSValidatorResult(cleanFlagSets, 0);
         }
-        TreeSet<String> cleanFlagSets = new TreeSet<>();
         int invalidSets = 0;
         for (String flagSet: flagSets) {
             if(flagSet != flagSet.toLowerCase()) {
@@ -42,12 +41,12 @@ public static FSValidatorResult cleanup(List<String> flagSets) {
             }
             cleanFlagSets.add(flagSet);
         }
-        return new FSValidatorResult(new ArrayList<>(cleanFlagSets), invalidSets);
+        return new FSValidatorResult(cleanFlagSets, invalidSets);
     }
 
     public static FlagSetsValidResult areValid(List<String> flagSets) {
         FSValidatorResult fsValidatorResult = cleanup(flagSets);
-        List<String> cleanFlagSets = fsValidatorResult.getFlagSets();
-        return new FlagSetsValidResult(cleanFlagSets != null && cleanFlagSets.size() != 0, new HashSet<>(cleanFlagSets));
+        HashSet cleanFlagSets = fsValidatorResult.getFlagSets();
+        return new FlagSetsValidResult(cleanFlagSets != null && cleanFlagSets.size() != 0, cleanFlagSets);
     }
 }
\ No newline at end of file
diff --git a/client/src/test/java/io/split/client/SplitClientImplTest.java b/client/src/test/java/io/split/client/SplitClientImplTest.java
index 964c8d563..5f33cf344 100644
--- a/client/src/test/java/io/split/client/SplitClientImplTest.java
+++ b/client/src/test/java/io/split/client/SplitClientImplTest.java
@@ -1733,7 +1733,7 @@ public void testTreatmentsByFlagSets() {
         fetchManyResult.put(test2, parsedSplit2);
         when(splitCacheConsumer.fetchMany(new ArrayList<>(Arrays.asList(test2, test)))).thenReturn(fetchManyResult);
 
-        List<String> sets = new ArrayList<>(Arrays.asList("set3", "set1"));
+        List<String> sets = new ArrayList<>(Arrays.asList("set1", "set3"));
         Map<String, HashSet<String>> flagsBySets = new HashMap<>();
         flagsBySets.put("set1", new HashSet<>(Arrays.asList(test)));
         flagsBySets.put("set3", new HashSet<>(Arrays.asList(test2)));
diff --git a/client/src/test/java/io/split/client/utils/FlagSetsValidatorTest.java b/client/src/test/java/io/split/client/utils/FlagSetsValidatorTest.java
index 449af5428..e9943fc8c 100644
--- a/client/src/test/java/io/split/client/utils/FlagSetsValidatorTest.java
+++ b/client/src/test/java/io/split/client/utils/FlagSetsValidatorTest.java
@@ -71,11 +71,12 @@ public void testFlagSetsInOrder() {
         flagSets.add(" 2test ");
         FSValidatorResult cleanFlagSets = cleanup(flagSets);
         Assert.assertEquals(5, cleanFlagSets.getFlagSets().size());
-        Assert.assertEquals("1test", cleanFlagSets.getFlagSets().get(0));
-        Assert.assertEquals("2test", cleanFlagSets.getFlagSets().get(1));
-        Assert.assertEquals("test1", cleanFlagSets.getFlagSets().get(2));
-        Assert.assertEquals("test2", cleanFlagSets.getFlagSets().get(3));
-        Assert.assertEquals("test3", cleanFlagSets.getFlagSets().get(4));
+        List<String> sets = new ArrayList<>(cleanFlagSets.getFlagSets());
+        Assert.assertEquals("1test", sets.get(0));
+        Assert.assertEquals("2test", sets.get(1));
+        Assert.assertEquals("test1", sets.get(2));
+        Assert.assertEquals("test2", sets.get(3));
+        Assert.assertEquals("test3", sets.get(4));
     }
 
     @Test