diff --git a/src/test/org/apache/commons/lang/StringUtilsSubstringTest.java b/src/test/org/apache/commons/lang/StringUtilsSubstringTest.java
index d9decb430..9ee752e5c 100644
--- a/src/test/org/apache/commons/lang/StringUtilsSubstringTest.java
+++ b/src/test/org/apache/commons/lang/StringUtilsSubstringTest.java
@@ -249,6 +249,8 @@ public class StringUtilsSubstringTest extends TestCase {
             
     public void testSubstringBetween_StringStringString() {
         assertEquals(null, StringUtils.substringBetween(null, "", ""));
+        assertEquals(null, StringUtils.substringBetween("", null, ""));
+        assertEquals(null, StringUtils.substringBetween("", "", null));
         assertEquals("", StringUtils.substringBetween("", "", ""));
         assertEquals("", StringUtils.substringBetween("foo", "", ""));
         assertEquals(null, StringUtils.substringBetween("foo", "", "]"));