diff --git a/lib/Doctrine/Table.php b/lib/Doctrine/Table.php
index faac80574..535d57ccf 100644
--- a/lib/Doctrine/Table.php
+++ b/lib/Doctrine/Table.php
@@ -880,7 +880,9 @@ public function addCheckConstraint($definition, $name)
     public function addIndex($index, array $definition)
     {
         if (isset($definition['fields'])) {
-            foreach ((array) $definition['fields'] as $key => $field) {
+            $definition['fields'] = (array) $definition['fields'];
+
+            foreach ($definition['fields'] as $key => $field) {
                 if (is_numeric($key)) {
                     $definition['fields'][$key] = $this->getColumnName($field);
                 } else {
diff --git a/tests/Table/IndexesUsingSingleFieldStringTestCase.php b/tests/Table/IndexesUsingSingleFieldStringTestCase.php
new file mode 100644
index 000000000..21300f41a
--- /dev/null
+++ b/tests/Table/IndexesUsingSingleFieldStringTestCase.php
@@ -0,0 +1,22 @@
+<?php
+
+class Doctrine_Table_IndexesUsingSingleFieldString_TestCase extends Doctrine_UnitTestCase
+{
+    protected $tables = array('IndexDeclaredWithSingleFieldStringRecord');
+
+    public function testSupportIndexesUsingSingleFieldString()
+    {
+    }
+}
+
+class IndexDeclaredWithSingleFieldStringRecord extends Doctrine_Record
+{
+    public function setTableDefinition()
+    {
+        $this->hasColumn('some_column_name', 'string', 255);
+
+        $this->index('single_field_index_as_string', array(
+            'fields' => 'some_column_name',
+        ));
+    }
+}
diff --git a/tests/run.php b/tests/run.php
index d1dd2c7ee..16fe619fa 100644
--- a/tests/run.php
+++ b/tests/run.php
@@ -140,6 +140,7 @@
 $core->addTestCase(new Doctrine_Table_TestCase());
 $core->addTestCase(new Doctrine_Table_RemoveColumn_TestCase());
 $core->addTestCase(new Doctrine_Table_NamedQuery_TestCase());
+$core->addTestCase(new Doctrine_Table_IndexesUsingSingleFieldString_TestCase());
 $core->addTestCase(new Doctrine_UnitOfWork_TestCase());
 $core->addTestCase(new Doctrine_Collection_TestCase());
 $core->addTestCase(new Doctrine_Collection_Snapshot_TestCase());