diff --git a/lib/private/DB/QueryBuilder/FunctionBuilder/PgSqlFunctionBuilder.php b/lib/private/DB/QueryBuilder/FunctionBuilder/PgSqlFunctionBuilder.php
index 27ebf1a04f..26aedb9a8b 100644
--- a/lib/private/DB/QueryBuilder/FunctionBuilder/PgSqlFunctionBuilder.php
+++ b/lib/private/DB/QueryBuilder/FunctionBuilder/PgSqlFunctionBuilder.php
@@ -25,6 +25,6 @@ use OC\DB\QueryBuilder\QueryFunction;
 
 class PgSqlFunctionBuilder extends FunctionBuilder {
 	public function concat($x, $y) {
-		return new QueryFunction($this->helper->quoteColumnName($x) . ' || ' . $this->helper->quoteColumnName($y));
+		return new QueryFunction('(' . $this->helper->quoteColumnName($x) . ' || ' . $this->helper->quoteColumnName($y) . ')');
 	}
 }
diff --git a/lib/private/DB/QueryBuilder/FunctionBuilder/SqliteFunctionBuilder.php b/lib/private/DB/QueryBuilder/FunctionBuilder/SqliteFunctionBuilder.php
index e985b7306a..f38445a6d3 100644
--- a/lib/private/DB/QueryBuilder/FunctionBuilder/SqliteFunctionBuilder.php
+++ b/lib/private/DB/QueryBuilder/FunctionBuilder/SqliteFunctionBuilder.php
@@ -25,6 +25,6 @@ use OC\DB\QueryBuilder\QueryFunction;
 
 class SqliteFunctionBuilder extends FunctionBuilder {
 	public function concat($x, $y) {
-		return new QueryFunction($this->helper->quoteColumnName($x) . ' || ' . $this->helper->quoteColumnName($y));
+		return new QueryFunction('(' . $this->helper->quoteColumnName($x) . ' || ' . $this->helper->quoteColumnName($y) . ')');
 	}
 }