diff --git a/conf/cassandra-env.ps1 b/conf/cassandra-env.ps1
index dbf83a3c30..8dddc2db84 100644
--- a/conf/cassandra-env.ps1
+++ b/conf/cassandra-env.ps1
@@ -389,7 +389,7 @@ Function SetCassandraEnvironment
     $env:JVM_OPTS="$env:JVM_OPTS -XX:MaxTenuringThreshold=1"
     $env:JVM_OPTS="$env:JVM_OPTS -XX:CMSInitiatingOccupancyFraction=75"
     $env:JVM_OPTS="$env:JVM_OPTS -XX:+UseCMSInitiatingOccupancyOnly"
-    $env:JVM_OPTS="$env:JVM_OPTS -XX:-PerfDisableSharedMem"
+    $env:JVM_OPTS="$env:JVM_OPTS -XX:+PerfDisableSharedMem"
     $env:JVM_OPTS="$env:JVM_OPTS -XX:+UseTLAB"
     if (($env:JVM_VERSION.CompareTo("1.7") -eq 1) -and ($env:JVM_ARCH -eq "64-Bit"))
     {
diff --git a/conf/cassandra-env.sh b/conf/cassandra-env.sh
index 7b9ea28f1a..2dba3f7f8a 100644
--- a/conf/cassandra-env.sh
+++ b/conf/cassandra-env.sh
@@ -266,7 +266,7 @@ JVM_OPTS="$JVM_OPTS -XX:MaxTenuringThreshold=1"
 JVM_OPTS="$JVM_OPTS -XX:CMSInitiatingOccupancyFraction=75"
 JVM_OPTS="$JVM_OPTS -XX:+UseCMSInitiatingOccupancyOnly"
 JVM_OPTS="$JVM_OPTS -XX:+UseTLAB"
-JVM_OPTS="$JVM_OPTS -XX:-PerfDisableSharedMem"
+JVM_OPTS="$JVM_OPTS -XX:+PerfDisableSharedMem"
 JVM_OPTS="$JVM_OPTS -XX:CompileCommandFile=$CASSANDRA_CONF/hotspot_compiler"
 JVM_OPTS="$JVM_OPTS -XX:CMSWaitDuration=10000"