diff --git a/src/Valitron/Validator.php b/src/Valitron/Validator.php
index ed04d77..0c0a844 100644
--- a/src/Valitron/Validator.php
+++ b/src/Valitron/Validator.php
@@ -420,9 +420,8 @@ class Validator
      */
     protected function validateIn($field, $value, $params)
     {
-        $isAssoc = array_values($params[0]) !== $params[0];
-        if ($isAssoc) {
-            $params[0] = array_keys($params[0]);
+        if ($this->isAssociativeArray($params[0])) {
+           $params[0] = array_keys($params[0]);
         }
 
         $strict = false;
@@ -443,8 +442,7 @@ class Validator
      */
     protected function validateListContains($field, $value, $params)
     {
-        $isAssoc = array_values($value) !== $value;
-        if ($isAssoc) {
+        if ($this->isAssociativeArray($value)) {
             $value = array_keys($value);
         }
 
@@ -1566,4 +1564,9 @@ class Validator
             $me->mapFieldRules($field, $rules[$field]);
         }, array_keys($rules));
     }
+
+    private function isAssociativeArray($input){
+        //array contains at least one key that's not an can not be cast to an integer
+        return count(array_filter(array_keys($input), 'is_string')) > 0;
+    }
 }
diff --git a/tests/Valitron/ValidateTest.php b/tests/Valitron/ValidateTest.php
index d086ea8..58b34da 100644
--- a/tests/Valitron/ValidateTest.php
+++ b/tests/Valitron/ValidateTest.php
@@ -4,6 +4,7 @@ use Valitron\Validator;
 
 class ValidateTest extends BaseTestCase
 {
+
     public function testValidWithNoRules()
     {
         $v = new Validator(array('name' => 'Chester Tester'));
@@ -2920,6 +2921,35 @@ class ValidateTest extends BaseTestCase
         $v->rule('optional', 'address');
         $this->assertTrue($v->validate());
     }
+
+    /**
+     *
+     * @see https://github.com/vlucas/valitron/issues/332
+     */
+    public function testInRuleSearchesValuesForNumericArray(){
+
+        $v = new Valitron\Validator(array('color' => 'purple'));
+
+        $v->rules(array(
+            'in' => array(
+                array('color', array(3=>'green', 2=>'purple'))
+            )
+        ));
+
+        $this->assertTrue($v->validate());
+    }
+
+    public function testInRuleSearchesKeysForAssociativeArray(){
+        $v = new Valitron\Validator(array('color' => 'purple'));
+
+        $v->rules(array(
+            'in' => array(
+                array('color', array('c-3'=>'green', 'c-2'=>'purple'))
+            )
+        ));
+
+        $this->assertFalse($v->validate());
+    }
 }
 
 function sampleFunctionCallback($field, $value, array $params)