Solr zkcli script failing with 'ClassNotFound' in 6.4.2

/opt/solr-dists/solr-6.4.2/server/scripts/cloud-scripts/zkcli.sh -zkhost localhost:9983/test -cmd bootstrap -solrhome /opt/solr-dists/solr-6.4.2/server/solr
Exception in thread "main" java.lang.NoClassDefFoundError: com/codahale/metrics/Metric
    at org.apache.solr.cloud.ZkCLI.main(ZkCLI.java:199)
Caused by: java.lang.ClassNotFoundException: com.codahale.metrics.Metric
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 1 more