diff --git a/src/com/android/contacts/format/FormatUtils.java b/src/com/android/contacts/format/FormatUtils.java
index 34a6078..c4f4930 100644
--- a/src/com/android/contacts/format/FormatUtils.java
+++ b/src/com/android/contacts/format/FormatUtils.java
@@ -134,10 +134,14 @@
      * @param prefix the text to find, in upper case letters
      */
     public static int indexOfWordPrefix(CharSequence text, char[] prefix) {
+        if (prefix == null || text == null) {
+            return -1;
+        }
+
         int textLength = text.length();
         int prefixLength = prefix.length;
 
-        if (prefix == null || prefixLength == 0 || textLength < prefixLength) {
+        if (prefixLength == 0 || textLength < prefixLength) {
             return -1;
         }
 
diff --git a/tests/src/com/android/contacts/format/FormatUtilsTests.java b/tests/src/com/android/contacts/format/FormatUtilsTests.java
index 42e2d53..c3e6236 100644
--- a/tests/src/com/android/contacts/format/FormatUtilsTests.java
+++ b/tests/src/com/android/contacts/format/FormatUtilsTests.java
@@ -71,6 +71,14 @@
         }
     }
 
+    public void testIndexOfWordPrefix_NullPrefix() {
+        assertEquals(-1, FormatUtils.indexOfWordPrefix("test", null));
+    }
+
+    public void testIndexOfWordPrefix_NullText() {
+        assertEquals(-1, FormatUtils.indexOfWordPrefix(null, "TE".toCharArray()));
+    }
+
     public void testIndexOfWordPrefix_MatchingPrefix() {
         checkIndexOfWordPrefix("test", "TE", 0);
         checkIndexOfWordPrefix("Test", "TE", 0);