diff --git a/app/DoctrineMigrations/Version20130616122810.php b/app/DoctrineMigrations/Version20130616122810.php
index 0f09239..0485ad8 100644
--- a/app/DoctrineMigrations/Version20130616122810.php
+++ b/app/DoctrineMigrations/Version20130616122810.php
@@ -15,11 +15,27 @@ public function up(Schema $schema)
         // this up() migration is auto-generated, please modify it to your needs
         $this->abortIf($this->connection->getDatabasePlatform()->getName() != "mysql", "Migration can only be executed safely on 'mysql'.");
 
-        $this->addSql("ALTER TABLE os_user DROP FOREIGN KEY FK_7BB0CD52BF396750");
-        $this->addSql("ALTER TABLE os_clock ADD uid INT DEFAULT NULL");
-        $this->addSql("ALTER TABLE os_clock ADD CONSTRAINT FK_34E85465539B0606 FOREIGN KEY (uid) REFERENCES os_user (id)");
-        $this->addSql("UPDATE os_clock SET uid = id");
-        $this->addSql("CREATE UNIQUE INDEX UNIQ_34E85465539B0606 ON os_clock (uid)");
+        $tables = $schema->getTables();
+        foreach ($tables as $table) {
+            if ($table->getName() === "os_user") {
+                if ($table->hasForeignKey('FK_7BB0CD52BF396750')) {
+                    $this->addSql("ALTER TABLE os_user DROP FOREIGN KEY FK_7BB0CD52BF396750");
+                }
+            } else if ($table->getName() === "os_clock") {
+                if (!$table->hasColumn("uid")) {
+                    $this->addSql("ALTER TABLE os_clock ADD uid INT DEFAULT NULL");
+                    $this->addSql("UPDATE os_clock SET uid = id");
+                }
+
+                if (!$table->hasForeignKey('FK_34E85465539B0606')) {
+                    $this->addSql("ALTER TABLE os_clock ADD CONSTRAINT FK_34E85465539B0606 FOREIGN KEY (uid) REFERENCES os_user (id)");
+                }
+
+                if (!$table->hasIndex('UNIQ_34E85465539B0606')) {
+                    $this->addSql("CREATE UNIQUE INDEX UNIQ_34E85465539B0606 ON os_clock (uid)");
+                }
+            }
+        }
     }
 
     public function down(Schema $schema)
diff --git a/app/DoctrineMigrations/Version20130616165301.php b/app/DoctrineMigrations/Version20130616165301.php
index eaba8b4..cddfff8 100644
--- a/app/DoctrineMigrations/Version20130616165301.php
+++ b/app/DoctrineMigrations/Version20130616165301.php
@@ -15,7 +15,12 @@ public function up(Schema $schema)
         // this up() migration is auto-generated, please modify it to your needs
         $this->abortIf($this->connection->getDatabasePlatform()->getName() != "mysql", "Migration can only be executed safely on 'mysql'.");
 
-        $this->addSql("ALTER TABLE os_settings ADD massEmail VARCHAR(255) DEFAULT NULL");
+        if ($schema->hasTable('os_settings')) {
+            $table = $schema->getTable('os_settings');
+            if (!$table->hasColumn('massEmail')) {
+                $this->addSql("ALTER TABLE os_settings ADD massEmail VARCHAR(255) DEFAULT NULL");
+            }
+        }
     }
 
     public function down(Schema $schema)
@@ -23,6 +28,11 @@ public function down(Schema $schema)
         // this down() migration is auto-generated, please modify it to your needs
         $this->abortIf($this->connection->getDatabasePlatform()->getName() != "mysql", "Migration can only be executed safely on 'mysql'.");
 
-        $this->addSql("ALTER TABLE os_settings DROP massEmail");
+        if ($schema->hasTable('os_settings')) {
+            $table = $schema->getTable('os_settings');
+            if (!$table->hasColumn('massEmail')) {
+                $this->addSql("ALTER TABLE os_settings DROP massEmail");
+            }
+        }
     }
 }