diff --git a/hadoop-common-project/hadoop-common/CHANGES.txt b/hadoop-common-project/hadoop-common/CHANGES.txt
index 3b1adcf51da..5cb490eca61 100644
--- a/hadoop-common-project/hadoop-common/CHANGES.txt
+++ b/hadoop-common-project/hadoop-common/CHANGES.txt
@@ -81,6 +81,9 @@ Release 0.23.1 - Unreleased
 
     HADOOP-7939. Improve Hadoop subcomponent integration in Hadoop 0.23. (rvs via tucu)
 
+    HADOOP-7988. Upper case in hostname part of the principals doesn't work with
+    kerberos. (jitendra)
+
   OPTIMIZATIONS
 
   BUG FIXES
diff --git a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/SecurityUtil.java b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/SecurityUtil.java
index a72b1f272ca..abf9f3aa80a 100644
--- a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/SecurityUtil.java
+++ b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/SecurityUtil.java
@@ -236,7 +236,7 @@ public class SecurityUtil {
     if (fqdn == null || fqdn.equals("") || fqdn.equals("0.0.0.0")) {
       fqdn = getLocalHostName();
     }
-    return components[0] + "/" + fqdn + "@" + components[2];
+    return components[0] + "/" + fqdn.toLowerCase() + "@" + components[2];
   }
   
   static String getLocalHostName() throws UnknownHostException {
diff --git a/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/security/TestSecurityUtil.java b/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/security/TestSecurityUtil.java
index 84f585b5999..57a1e116de7 100644
--- a/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/security/TestSecurityUtil.java
+++ b/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/security/TestSecurityUtil.java
@@ -89,6 +89,16 @@ public class TestSecurityUtil {
     Mockito.verify(notUsed, Mockito.never()).getCanonicalHostName();
   }
 
+  @Test
+  public void testPrincipalsWithLowerCaseHosts() throws IOException {
+    String service = "xyz/";
+    String realm = "@REALM";
+    String principalInConf = service + SecurityUtil.HOSTNAME_PATTERN + realm;
+    String hostname = "FooHost";
+    String principal = service + hostname.toLowerCase() + realm;
+    verify(principalInConf, hostname, principal);
+  }
+
   @Test
   public void testLocalHostNameForNullOrWild() throws Exception {
     String local = SecurityUtil.getLocalHostName();