diff --git a/make-distribution.sh b/make-distribution.sh
index a101024de54ae779c5b755bd8e5f76f6bc2c612d..55dc22b99270c099d760f69d5b25f378b84a8bc9 100755
--- a/make-distribution.sh
+++ b/make-distribution.sh
@@ -47,7 +47,7 @@ VERSION=$($FWDIR/sbt/sbt "show version" | tail -1 | cut -f 2 | sed 's/^\([a-zA-Z
 
 # Initialize defaults
 SPARK_HADOOP_VERSION=1.2.1
-SPARK_YARN_MODE=false
+SPARK_WITH_YARN=false
 MAKE_TGZ=false
 
 # Parse arguments
@@ -58,7 +58,7 @@ while (( "$#" )); do
       shift
       ;;
     --with-yarn)
-      SPARK_YARN_MODE=true
+      SPARK_WITH_YARN=true
       ;;
     --tgz)
       MAKE_TGZ=true
@@ -74,7 +74,7 @@ else
 fi
 
 echo "Hadoop version set to $SPARK_HADOOP_VERSION"
-if [ "$SPARK_YARN_MODE" == "true" ]; then
+if [ "$SPARK_WITH_YARN" == "true" ]; then
   echo "YARN enabled"
 else
   echo "YARN disabled"
@@ -82,7 +82,7 @@ fi
 
 # Build fat JAR
 export SPARK_HADOOP_VERSION
-export SPARK_YARN_MODE
+export SPARK_WITH_YARN
 "$FWDIR/sbt/sbt" "repl/assembly"
 
 # Make directories
diff --git a/project/SparkBuild.scala b/project/SparkBuild.scala
index 4023626c16a3368fd1e73af95fc2346f0719bec6..cea982b8860e2234d2880300d80832ab8a4d1b3b 100644
--- a/project/SparkBuild.scala
+++ b/project/SparkBuild.scala
@@ -26,8 +26,10 @@ import AssemblyKeys._
 object SparkBuild extends Build {
   // Hadoop version to build against. For example, "0.20.2", "0.20.205.0", or
   // "1.0.4" for Apache releases, or "0.20.2-cdh3u5" for Cloudera Hadoop.
-  val HADOOP_VERSION = "1.2.1"
-  val HADOOP_YARN = false
+  // Note that these variables can be set through the environment variables
+  // SPARK_HADOOP_VERSION and SPARK_WITH_YARN.
+  val DEFAULT_HADOOP_VERSION = "1.2.1"
+  val DEFAULT_WITH_YARN = false
 
   // HBase version; set as appropriate.
   val HBASE_VERSION = "0.94.6"
@@ -55,9 +57,9 @@ object SparkBuild extends Build {
   lazy val publishLocalBoth = TaskKey[Unit]("publish-local", "publish local for m2 and ivy")
 
   // Allows build configuration to be set through environment variables
-  lazy val hadoopVersion = scala.util.Properties.envOrElse("SPARK_HADOOP_VERSION", HADOOP_VERSION)
-  lazy val isYarnMode = scala.util.Properties.envOrNone("SPARK_YARN_MODE") match {
-    case None => HADOOP_YARN
+  lazy val hadoopVersion = scala.util.Properties.envOrElse("SPARK_HADOOP_VERSION", DEFAULT_HADOOP_VERSION)
+  lazy val isYarnMode = scala.util.Properties.envOrNone("SPARK_WITH_YARN") match {
+    case None => DEFAULT_WITH_YARN
     case Some(v) => v.toBoolean
   }