diff --git a/hadoop-common-project/hadoop-common/CHANGES.txt b/hadoop-common-project/hadoop-common/CHANGES.txt
index 7eafd25a90..50d2673d28 100644
--- a/hadoop-common-project/hadoop-common/CHANGES.txt
+++ b/hadoop-common-project/hadoop-common/CHANGES.txt
@@ -100,6 +100,20 @@ Trunk (unreleased changes)
     HADOOP-7773. Add support for protocol buffer based RPC engine.
     (suresh)
 
+Release 0.23.1 - Unreleased
+
+  INCOMPATIBLE CHANGES
+
+  NEW FEATURES                                                                    
+
+  IMPROVEMENTS
+
+    HADOOP-7801. HADOOP_PREFIX cannot be overriden. (Bruno Mahé via tomwhite)
+
+  OPTIMIZATIONS
+
+  BUG FIXES
+
 Release 0.23.0 - 2011-11-01 
 
   INCOMPATIBLE CHANGES
diff --git a/hadoop-common-project/hadoop-common/src/main/bin/hadoop-config.sh b/hadoop-common-project/hadoop-common/src/main/bin/hadoop-config.sh
index 5f248fdf53..8bf9aecef4 100644
--- a/hadoop-common-project/hadoop-common/src/main/bin/hadoop-config.sh
+++ b/hadoop-common-project/hadoop-common/src/main/bin/hadoop-config.sh
@@ -27,7 +27,9 @@ this="$common_bin/$script"
 
 # the root of the Hadoop installation
 # See HADOOP-6255 for directory structure layout
-export HADOOP_PREFIX=`dirname "$this"`/..
+HADOOP_DEFAULT_PREFIX=`dirname "$this"`/..
+HADOOP_PREFIX=${HADOOP_PREFIX:-$HADOOP_DEFAULT_PREFIX}
+export HADOOP_PREFIX
 
 #check to see if the conf dir is given as an optional argument
 if [ $# -gt 1 ]
diff --git a/hadoop-common-project/hadoop-common/src/main/packages/deb/init.d/hadoop-datanode b/hadoop-common-project/hadoop-common/src/main/packages/deb/init.d/hadoop-datanode
index 81795879cf..658f6d7574 100644
--- a/hadoop-common-project/hadoop-common/src/main/packages/deb/init.d/hadoop-datanode
+++ b/hadoop-common-project/hadoop-common/src/main/packages/deb/init.d/hadoop-datanode
@@ -75,7 +75,7 @@ check_privsep_dir() {
 }
 
 export PATH="${PATH:+$PATH:}/usr/sbin:/usr/bin"
-export HADOOP_PREFIX="/usr"
+export HADOOP_PREFIX=${HADOOP_PREFIX:-/usr}
 
 case "$1" in
   start)
diff --git a/hadoop-common-project/hadoop-common/src/main/packages/deb/init.d/hadoop-jobtracker b/hadoop-common-project/hadoop-common/src/main/packages/deb/init.d/hadoop-jobtracker
index c483d76a17..8958da35de 100644
--- a/hadoop-common-project/hadoop-common/src/main/packages/deb/init.d/hadoop-jobtracker
+++ b/hadoop-common-project/hadoop-common/src/main/packages/deb/init.d/hadoop-jobtracker
@@ -67,7 +67,7 @@ check_privsep_dir() {
 }
 
 export PATH="${PATH:+$PATH:}/usr/sbin:/usr/bin"
-export HADOOP_PREFIX="/usr"
+export HADOOP_PREFIX=${HADOOP_PREFIX:-/usr}
 
 case "$1" in
   start)
diff --git a/hadoop-common-project/hadoop-common/src/main/packages/deb/init.d/hadoop-namenode b/hadoop-common-project/hadoop-common/src/main/packages/deb/init.d/hadoop-namenode
index e2608769d4..6e5485cc8a 100644
--- a/hadoop-common-project/hadoop-common/src/main/packages/deb/init.d/hadoop-namenode
+++ b/hadoop-common-project/hadoop-common/src/main/packages/deb/init.d/hadoop-namenode
@@ -71,7 +71,7 @@ format() {
 }
 
 export PATH="${PATH:+$PATH:}/usr/sbin:/usr/bin"
-export HADOOP_PREFIX="/usr"
+export HADOOP_PREFIX=${HADOOP_PREFIX:-/usr}
 
 case "$1" in
   start)
diff --git a/hadoop-common-project/hadoop-common/src/main/packages/deb/init.d/hadoop-tasktracker b/hadoop-common-project/hadoop-common/src/main/packages/deb/init.d/hadoop-tasktracker
index 983030bbb6..ca36cd6f45 100644
--- a/hadoop-common-project/hadoop-common/src/main/packages/deb/init.d/hadoop-tasktracker
+++ b/hadoop-common-project/hadoop-common/src/main/packages/deb/init.d/hadoop-tasktracker
@@ -67,7 +67,7 @@ check_privsep_dir() {
 }
 
 export PATH="${PATH:+$PATH:}/usr/sbin:/usr/bin"
-export HADOOP_PREFIX="/usr"
+export HADOOP_PREFIX=${HADOOP_PREFIX:-/usr}
 
 case "$1" in
   start)
diff --git a/hadoop-common-project/hadoop-common/src/main/packages/hadoop-setup-conf.sh b/hadoop-common-project/hadoop-common/src/main/packages/hadoop-setup-conf.sh
index db1f5b9e45..de47ce2716 100644
--- a/hadoop-common-project/hadoop-common/src/main/packages/hadoop-setup-conf.sh
+++ b/hadoop-common-project/hadoop-common/src/main/packages/hadoop-setup-conf.sh
@@ -19,7 +19,9 @@ bin=`dirname "$0"`
 bin=`cd "$bin"; pwd`
 
 this="${BASH_SOURCE-$0}"
-export HADOOP_PREFIX=`dirname "$this"`/..
+HADOOP_DEFAULT_PREFIX=`dirname "$this"`/..
+HADOOP_PREFIX=${HADOOP_PREFIX:-$HADOOP_DEFAULT_PREFIX}
+export HADOOP_PREFIX
 
 usage() {
   echo "
diff --git a/hadoop-common-project/hadoop-common/src/main/packages/rpm/init.d/hadoop-jobtracker b/hadoop-common-project/hadoop-common/src/main/packages/rpm/init.d/hadoop-jobtracker
index 5c2272b8fd..9e85c66ee9 100644
--- a/hadoop-common-project/hadoop-common/src/main/packages/rpm/init.d/hadoop-jobtracker
+++ b/hadoop-common-project/hadoop-common/src/main/packages/rpm/init.d/hadoop-jobtracker
@@ -27,7 +27,7 @@ source /etc/default/hadoop-env.sh
 RETVAL=0
 PIDFILE="${HADOOP_PID_DIR}/hadoop-mapred-jobtracker.pid"
 desc="Hadoop jobtracker daemon"
-export HADOOP_PREFIX="/usr"
+export HADOOP_PREFIX=${HADOOP_PREFIX:-/usr}
 
 start() {
   echo -n $"Starting $desc (hadoop-jobtracker): "
diff --git a/hadoop-common-project/hadoop-common/src/main/packages/rpm/init.d/hadoop-namenode b/hadoop-common-project/hadoop-common/src/main/packages/rpm/init.d/hadoop-namenode
index 4e7f74b046..3067f03ef5 100644
--- a/hadoop-common-project/hadoop-common/src/main/packages/rpm/init.d/hadoop-namenode
+++ b/hadoop-common-project/hadoop-common/src/main/packages/rpm/init.d/hadoop-namenode
@@ -27,7 +27,7 @@ source /etc/default/hadoop-env.sh
 RETVAL=0
 PIDFILE="${HADOOP_PID_DIR}/hadoop-hdfs-namenode.pid"
 desc="Hadoop namenode daemon"
-export HADOOP_PREFIX="/usr"
+export HADOOP_PREFIX=${HADOOP_PREFIX:-/usr}
 
 start() {
   echo -n $"Starting $desc (hadoop-namenode): "
diff --git a/hadoop-common-project/hadoop-common/src/main/packages/rpm/init.d/hadoop-tasktracker b/hadoop-common-project/hadoop-common/src/main/packages/rpm/init.d/hadoop-tasktracker
index 2d06c5a9c9..9a57f56275 100644
--- a/hadoop-common-project/hadoop-common/src/main/packages/rpm/init.d/hadoop-tasktracker
+++ b/hadoop-common-project/hadoop-common/src/main/packages/rpm/init.d/hadoop-tasktracker
@@ -27,7 +27,7 @@ source /etc/default/hadoop-env.sh
 RETVAL=0
 PIDFILE="${HADOOP_PID_DIR}/hadoop-mapred-tasktracker.pid"
 desc="Hadoop tasktracker daemon"
-export HADOOP_PREFIX="/usr"
+export HADOOP_PREFIX=${HADOOP_PREFIX:-/usr}
 
 start() {
   echo -n $"Starting $desc (hadoop-tasktracker): "