diff --git a/unsafe/src/main/java/org/apache/spark/unsafe/types/UTF8String.java b/unsafe/src/main/java/org/apache/spark/unsafe/types/UTF8String.java
index bc46ca52aa284..474ea58c8d465 100644
--- a/unsafe/src/main/java/org/apache/spark/unsafe/types/UTF8String.java
+++ b/unsafe/src/main/java/org/apache/spark/unsafe/types/UTF8String.java
@@ -125,37 +125,37 @@ public UTF8String substring(final int start, final int until) {
   }
 
   public boolean contains(final UTF8String substring) {
+    if (substring == null) return false;
     final byte[] b = substring.getBytes();
     if (b.length == 0) {
       return true;
     }
 
     for (int i = 0; i <= bytes.length - b.length; i++) {
-      if (bytes[i] == b[0] && startsWith(substring, i)) {
+      if (bytes[i] == b[0] && startsWith(b, i)) {
         return true;
       }
     }
     return false;
   }
 
-  private boolean startsWith(final UTF8String prefix, int offset) {
-    byte[] b = prefix.getBytes();
-    if (b.length + offset > bytes.length || offset < 0) {
+  private boolean startsWith(final byte[] prefix, int offset) {
+    if (prefix.length + offset > bytes.length || offset < 0) {
       return false;
     }
     int i = 0;
-    while (i < b.length && b[i] == bytes[i + offset]) {
+    while (i < prefix.length && prefix[i] == bytes[i + offset]) {
       i++;
     }
-    return i == b.length;
+    return i == prefix.length;
   }
 
   public boolean startsWith(final UTF8String prefix) {
-    return startsWith(prefix, 0);
+    return prefix != null && startsWith(prefix.getBytes(), 0);
   }
 
   public boolean endsWith(final UTF8String suffix) {
-    return startsWith(suffix, bytes.length - suffix.getBytes().length);
+    return suffix != null && startsWith(suffix.getBytes(), bytes.length - suffix.getBytes().length);
   }
 
   public UTF8String toUpperCase() {
diff --git a/unsafe/src/test/java/org/apache/spark/unsafe/types/UTF8StringSuite.java b/unsafe/src/test/java/org/apache/spark/unsafe/types/UTF8StringSuite.java
index 80c179a1b5e75..f0f530418b08f 100644
--- a/unsafe/src/test/java/org/apache/spark/unsafe/types/UTF8StringSuite.java
+++ b/unsafe/src/test/java/org/apache/spark/unsafe/types/UTF8StringSuite.java
@@ -46,6 +46,7 @@ public void basicTest() throws UnsupportedEncodingException {
 
   @Test
   public void contains() {
+    Assert.assertFalse(UTF8String.fromString("hello").contains(null));
     Assert.assertTrue(UTF8String.fromString("hello").contains(UTF8String.fromString("ello")));
     Assert.assertFalse(UTF8String.fromString("hello").contains(UTF8String.fromString("vello")));
     Assert.assertFalse(UTF8String.fromString("hello").contains(UTF8String.fromString("hellooo")));
@@ -57,6 +58,7 @@ public void contains() {
 
   @Test
   public void startsWith() {
+    Assert.assertFalse(UTF8String.fromString("hello").startsWith(null));
     Assert.assertTrue(UTF8String.fromString("hello").startsWith(UTF8String.fromString("hell")));
     Assert.assertFalse(UTF8String.fromString("hello").startsWith(UTF8String.fromString("ell")));
     Assert.assertFalse(UTF8String.fromString("hello").startsWith(UTF8String.fromString("hellooo")));
@@ -68,6 +70,7 @@ public void startsWith() {
 
   @Test
   public void endsWith() {
+    Assert.assertFalse(UTF8String.fromString("hello").endsWith(null));
     Assert.assertTrue(UTF8String.fromString("hello").endsWith(UTF8String.fromString("ello")));
     Assert.assertFalse(UTF8String.fromString("hello").endsWith(UTF8String.fromString("ellov")));
     Assert.assertFalse(UTF8String.fromString("hello").endsWith(UTF8String.fromString("hhhello")));