diff --git a/hadoop-common-project/hadoop-common/CHANGES.txt b/hadoop-common-project/hadoop-common/CHANGES.txt
index 3a7ebb80c36..868297f3e49 100644
--- a/hadoop-common-project/hadoop-common/CHANGES.txt
+++ b/hadoop-common-project/hadoop-common/CHANGES.txt
@@ -33,6 +33,9 @@ Release 2.5.0 - UNRELEASED
     HADOOP-10322. Add ability to read principal names from a keytab.
     (Benoy Antony and Daryn Sharp via kihwal)
 
+    HADOOP-10549. MAX_SUBST and varPat should be final in Configuration.java.
+    (Gera Shegalov via cnauroth)
+
   OPTIMIZATIONS
 
   BUG FIXES 
diff --git a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/Configuration.java b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/Configuration.java
index 18d4666ce06..a6243250ee1 100644
--- a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/Configuration.java
+++ b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/Configuration.java
@@ -797,14 +797,16 @@ public class Configuration implements Iterable<Map.Entry<String,String>>,
     reloadConfiguration();
   }
   
-  private static Pattern varPat = Pattern.compile("\\$\\{[^\\}\\$\u0020]+\\}");
-  private static int MAX_SUBST = 20;
+  private static final Pattern VAR_PATTERN =
+      Pattern.compile("\\$\\{[^\\}\\$\u0020]+\\}");
+
+  private static final int MAX_SUBST = 20;
 
   private String substituteVars(String expr) {
     if (expr == null) {
       return null;
     }
-    Matcher match = varPat.matcher("");
+    Matcher match = VAR_PATTERN.matcher("");
     String eval = expr;
     for(int s=0; s<MAX_SUBST; s++) {
       match.reset(eval);