diff --git a/src/Association/Apriori.php b/src/Association/Apriori.php
index c3f9c91..abbdf47 100644
--- a/src/Association/Apriori.php
+++ b/src/Association/Apriori.php
@@ -212,9 +212,9 @@ class Apriori implements Associator
      */
     private function frequent(array $samples): array
     {
-        return array_filter($samples, function ($entry) {
+        return array_values(array_filter($samples, function ($entry) {
             return $this->support($entry) >= $this->support;
-        });
+        }));
     }
 
     /**
@@ -234,7 +234,7 @@ class Apriori implements Associator
                     continue;
                 }
 
-                $candidate = array_unique(array_merge($p, $q));
+                $candidate = array_values(array_unique(array_merge($p, $q)));
 
                 if ($this->contains($candidates, $candidate)) {
                     continue;
diff --git a/tests/Association/AprioriTest.php b/tests/Association/AprioriTest.php
index 5ed4f8c..81a6ce6 100644
--- a/tests/Association/AprioriTest.php
+++ b/tests/Association/AprioriTest.php
@@ -101,6 +101,18 @@ class AprioriTest extends TestCase
         $this->assertEquals([['a']], $L[1]);
     }
 
+    public function testAprioriL3(): void
+    {
+        $sample = [['a', 'b', 'c']];
+
+        $apriori = new Apriori(0, 0);
+        $apriori->train($sample, []);
+
+        $L = $apriori->apriori();
+
+        $this->assertEquals([['a', 'b', 'c']], $L[3]);
+    }
+
     public function testGetRules(): void
     {
         $apriori = new Apriori(0.4, 0.8);