diff --git a/google_adwords.install b/google_adwords.install
index d5fb161..cec8099 100644
--- a/google_adwords.install
+++ b/google_adwords.install
@@ -76,16 +76,35 @@ function google_adwords_schema() {
         'default' => '',
         'length' => 10,
       ),
-    ),
-  );
-
-  return $schema;
+			'color' => array(
+				'type' => 'varchar',
+			  'default' => '',
+			  'length' => 10,
+			),
+		),
+	);
+	return $schema;
 }
 
 function google_adwords_update_6001() {
-  $ret = array();
-  db_add_field($ret, 'google_adwords', 'format', array('type' => 'varchar', 'length' => 10));
-  db_add_field($ret, 'google_adwords', 'color', array('type' => 'varchar', 'length' => 10));
-  return $ret;
+	$ret = array();
+	if (!db_column_exists('google_adwords', 'format')) {
+		db_add_field($ret, 'google_adwords', 'format',
+			array(
+		   	'type' => 'varchar',
+		   	'default' => '',
+		   	'length' => 10,
+		  )
+		);
+	}
+	if (!db_column_exists('google_adwords', 'color')) {
+		db_add_field($ret, 'google_adwords', 'color',
+			array(
+		   	'type' => 'varchar',
+		   	'default' => '',
+		   	'length' => 10,
+		  )
+		);
+	}
+	return $ret;
 }
-