diff --git a/includes/data-stores/class-wc-order-data-store-cpt.php b/includes/data-stores/class-wc-order-data-store-cpt.php
index d8b1137b539..a346dcb0e35 100644
--- a/includes/data-stores/class-wc-order-data-store-cpt.php
+++ b/includes/data-stores/class-wc-order-data-store-cpt.php
@@ -383,7 +383,7 @@ class WC_Order_Data_Store_CPT extends Abstract_WC_Order_Data_Store_CPT implement
 			$wp_query_args['paged'] = absint( $args['page'] );
 		}
 
-		if ( ! empty( $args['customer'] ) ) {
+		if ( isset( $args['customer'] ) && '' !== $args['customer'] ) {
 			$values = is_array( $args['customer'] ) ? $args['customer'] : array( $args['customer'] );
 			$wp_query_args['meta_query'][] = $this->get_orders_generate_customer_meta_query( $values );
 		}
diff --git a/tests/unit-tests/order/functions.php b/tests/unit-tests/order/functions.php
index 3e6c76d660d..468cec96dda 100644
--- a/tests/unit-tests/order/functions.php
+++ b/tests/unit-tests/order/functions.php
@@ -148,44 +148,96 @@ class WC_Tests_Order_Functions extends WC_Unit_Test_Case {
 		$this->assertCount( 1, $order->get_payment_tokens() );
 	}
 
+	/**
+	 * Test the before and after date parameters for wc_get_orders.
+	 *
+	 * @since 3.0
+	 */
+	public function test_wc_get_orders_customer_params() {
+		$order1  = WC_Helper_Order::create_order( 0 );
+		$order2  = WC_Helper_Order::create_order( 0 );
+		$order3  = WC_Helper_Order::create_order( 1 );
+		$order4  = WC_Helper_Order::create_order( 1 );
+		$order_1 = $order1->get_id();
+		$order_2 = $order2->get_id();
+		$order_3 = $order3->get_id();
+		$order_4 = $order4->get_id();
+
+		$orders   = wc_get_orders( array( 'customer' => 0, 'return' => 'ids' ) );
+		$expected = array( $order_1, $order_2 );
+		sort( $expected );
+		sort( $orders );
+		$this->assertEquals( $expected, $orders );
+
+		$orders   = wc_get_orders( array( 'customer' => 1, 'return' => 'ids' ) );
+		$expected = array( $order_3, $order_4 );
+		sort( $expected );
+		sort( $orders );
+		$this->assertEquals( $expected, $orders );
+
+		$orders   = wc_get_orders( array( 'customer' => '', 'return' => 'ids' ) );
+		$expected = array( $order_1, $order_2, $order_3, $order_4 );
+		sort( $expected );
+		sort( $orders );
+		$this->assertEquals( $expected, $orders );
+
+		$order1->delete();
+		$order2->delete();
+		$order3->delete();
+		$order4->delete();
+	}
+
 	/**
 	 * Test the before and after date parameters for wc_get_orders.
 	 *
 	 * @since 3.0
 	 */
 	public function test_wc_get_orders_date_params() {
-		$order = WC_Helper_Order::create_order();
-		$order->set_date_created( '2015-01-01 05:20:30' );
-		$order->save();
-		$order_1 = $order->get_id();
-		$order   = WC_Helper_Order::create_order();
-		$order->set_date_created( '2017-01-01' );
-		$order->save();
-		$order_2 = $order->get_id();
-		$order   = WC_Helper_Order::create_order();
-		$order->set_date_created( '2017-01-01' );
-		$order->save();
-		$order_3 = $order->get_id();
+		$order1 = WC_Helper_Order::create_order();
+		$order1->set_date_created( '2015-01-01 05:20:30' );
+		$order1->save();
+		$order_1 = $order1->get_id();
+		$order2   = WC_Helper_Order::create_order();
+		$order2->set_date_created( '2017-01-01' );
+		$order2->save();
+		$order_2 = $order2->get_id();
+		$order3   = WC_Helper_Order::create_order();
+		$order3->set_date_created( '2017-01-01' );
+		$order3->save();
+		$order_3 = $order3->get_id();
 
 		$orders   = wc_get_orders( array( 'date_before' => '2017-01-15', 'return' => 'ids' ) );
 		$expected = array( $order_1, $order_2, $order_3 );
-		$this->assertEquals( sort( $expected ), sort( $orders ) );
+		sort( $expected );
+		sort( $orders );
+		$this->assertEquals( $expected, $orders );
 
 		$orders   = wc_get_orders( array( 'date_before' => '2017-01-01', 'return' => 'ids' ) );
 		$expected = array( $order_1 );
-		$this->assertEquals( sort( $expected ), sort( $orders ) );
+		sort( $expected );
+		sort( $orders );
+		$this->assertEquals( $expected, $orders );
 
 		$orders   = wc_get_orders( array( 'date_before' => '2016-12-31', 'return' => 'ids' ) );
 		$expected = array( $order_1 );
-		$this->assertEquals( sort( $expected ), sort( $orders ) );
+		sort( $expected );
+		sort( $orders );
+		$this->assertEquals( $expected, $orders );
 
 		$orders   = wc_get_orders( array( 'date_after' => '2015-01-01 00:00:00', 'return' => 'ids' ) );
 		$expected = array( $order_1, $order_2, $order_3 );
-		$this->assertEquals( sort( $expected ), sort( $orders ) );
+		sort( $expected );
+		sort( $orders );
+		$this->assertEquals( $expected, $orders );
 
 		$orders   = wc_get_orders( array( 'date_after' => '2016-01-01', 'return' => 'ids' ) );
 		$expected = array( $order_2, $order_3 );
-		$this->assertEquals( sort( $expected ), sort( $orders ) );
+		sort( $expected );
+		sort( $orders );
+		$this->assertEquals( $expected, $orders );
 
+		$order1->delete();
+		$order2->delete();
+		$order3->delete();
 	}
 }