diff --git a/src/test/StringUtilsTest.java b/src/test/StringUtilsTest.java
index 0dba0cc..8380b8e 100644
--- a/src/test/StringUtilsTest.java
+++ b/src/test/StringUtilsTest.java
@@ -18,6 +18,16 @@ public void init() {
         su = new StringUtils();
     }
 
+    @Test
+    public void shouldReturnEmpty1() {
+        assertEquals("", su.replaceLast("", "", ""));
+    }
+
+    @Test
+    public void shouldReturnEmpty2() {
+        assertEquals("", su.replaceLast("", "ll", "xx"));
+    }
+
     @Test
     public void shouldReturnHeo() {
         assertEquals("heo", su.replaceLast("hello", "ll", ""));