diff --git a/tests/codeigniter/database/query_builder/join_test.php b/tests/codeigniter/database/query_builder/join_test.php
index 58cb214..54b2a4e 100644
--- a/tests/codeigniter/database/query_builder/join_test.php
+++ b/tests/codeigniter/database/query_builder/join_test.php
@@ -37,6 +37,29 @@
 
 	// ------------------------------------------------------------------------
 
+	public function test_join_escape_is_null()
+	{
+		$expected = 'SELECT '.$this->db->escape_identifiers('field')
+				."\nFROM ".$this->db->escape_identifiers('table1')
+				."\nJOIN ".$this->db->escape_identifiers('table2').' ON '.$this->db->escape_identifiers('field').' IS NULL';
+
+		$this->assertEquals(
+			$expected,
+			$this->db->select('field')->from('table1')->join('table2', 'field IS NULL')->get_compiled_select()
+		);
+
+		$expected = 'SELECT '.$this->db->escape_identifiers('field')
+				."\nFROM ".$this->db->escape_identifiers('table1')
+				."\nJOIN ".$this->db->escape_identifiers('table2').' ON '.$this->db->escape_identifiers('field').' IS NOT NULL';
+
+		$this->assertEquals(
+			$expected,
+			$this->db->select('field')->from('table1')->join('table2', 'field IS NOT NULL')->get_compiled_select()
+		);
+	}
+
+	// ------------------------------------------------------------------------
+
 	public function test_join_escape_multiple_conditions()
 	{
 		// We just need a valid query produced, not one that makes sense
@@ -65,11 +88,11 @@
 		$expected = 'SELECT '.implode(', ', $fields)
 				."\nFROM ".$this->db->escape_identifiers('table1')
 				."\nRIGHT JOIN ".$this->db->escape_identifiers('table2').' ON '.implode(' = ', $fields)
-				.' AND ('.$fields[0]." = 'foo' OR ".$fields[1].' = 0)';
+				.' AND ('.$fields[0]." = 'foo' OR ".$fields[1].' IS NULL)';
 
 		$result = $this->db->select('table1.field1, table2.field2')
 				->from('table1')
-				->join('table2', "table1.field1 = table2.field2 AND (table1.field1 = 'foo' OR table2.field2 = 0)", 'RIGHT')
+				->join('table2', "table1.field1 = table2.field2 AND (table1.field1 = 'foo' OR table2.field2 IS NULL)", 'RIGHT')
 				->get_compiled_select();
 
 		$this->assertEquals($expected, $result);