diff --git a/README.md b/README.md
index e863c3e..2fce317 100644
--- a/README.md
+++ b/README.md
@@ -9,6 +9,8 @@ _Note:_ This system was built for Java 1.6 with ant. Set JAVA_HOME to a local Ja
 $ /usr/libexec/java_home -v 1.6
 $ export JAVA_HOME=<output-of-above-command>
 ```
+Note that you may also need to delete the `./server/bin` directory to remove old versions of the `KefedJettyServer` class if you get `Exception in thread "main" java.lang.UnsupportedClassVersionError: edu/isi/bmkeg/kefed/server/KefedJettyServer : Unsupported major.minor version 52.0` errors.
+
 *Build the system*
 ```
 $ cd editor