diff --git a/app/DoctrineMigrations/Version20170719231144.php b/app/DoctrineMigrations/Version20170719231144.php
new file mode 100644
index 000000000..691eae515
--- /dev/null
+++ b/app/DoctrineMigrations/Version20170719231144.php
@@ -0,0 +1,103 @@
+<?php
+
+namespace Application\Migrations;
+
+use Doctrine\DBAL\Migrations\AbstractMigration;
+use Doctrine\DBAL\Schema\Schema;
+use Symfony\Component\DependencyInjection\ContainerAwareInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Changed tags to lowercase
+ */
+class Version20170719231144 extends AbstractMigration implements ContainerAwareInterface
+{
+    /**
+     * @var ContainerInterface
+     */
+    private $container;
+
+    public function setContainer(ContainerInterface $container = null)
+    {
+        $this->container = $container;
+    }
+
+    private function getTable($tableName)
+    {
+        return $this->container->getParameter('database_table_prefix').$tableName;
+    }
+
+    /**
+     * @param Schema $schema
+     */
+    public function up(Schema $schema)
+    {
+        $this->skipIf($this->connection->getDatabasePlatform()->getName() == 'sqlite', 'Migration can only be executed safely on \'mysql\' or \'postgresql\'.');
+        
+        // Find tags which need to be merged
+        $dupTags = $this->connection->query("
+            SELECT LOWER(label)
+            FROM   ".$this->getTable('tag')."
+            GROUP BY LOWER(label)
+            HAVING COUNT(*) > 1"
+        );
+        $dupTags->execute();
+
+        foreach ($dupTags->fetchAll() as $duplicates) {
+            $label = $duplicates['LOWER(label)'];
+
+            // Retrieve all duplicate tags for a given tag
+            $tags = $this->connection->query("
+                SELECT id
+                FROM   ".$this->getTable('tag')."
+                WHERE  LOWER(label) = '".$label."'
+                ORDER BY id ASC"
+            );
+            $tags->execute();
+
+            $first = true;
+            $newId = null;
+            $ids = [];
+
+            foreach ($tags->fetchAll() as $tag) {
+                // Ignore the first tag as we use it as the new reference tag
+                if ($first) {
+                    $first = false;
+                    $newId = $tag['id'];
+                } else {
+                    $ids[] = $tag['id'];
+                }
+            }
+
+            // Just in case...
+            if (count($ids) > 0) {
+                // Merge tags
+                $this->addSql("
+                    UPDATE ".$this->getTable('entry_tag')."
+                    SET    tag_id = ".$newId."
+                    WHERE  tag_id IN (".implode(',', $ids).")"
+                );
+
+                // Delete unused tags
+                $this->addSql("
+                    DELETE FROM ".$this->getTable('tag')."
+                    WHERE id IN (".implode(',', $ids).")"
+                );
+            }
+        }
+
+        // Iterate over all tags to lowercase them
+        $this->addSql("
+            UPDATE ".$this->getTable('tag')."
+            SET label = LOWER(label)"
+        );
+    }
+
+    /**
+     * @param Schema $schema
+     */
+    public function down(Schema $schema)
+    {
+        throw new SkipMigrationException('Too complex ...');
+    }
+}