diff --git a/CHANGES.txt b/CHANGES.txt
index a362f786d5..c399c0d0d6 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -61,6 +61,7 @@
  * Add a system property to set hostId if not yet initialized (CASSANDRA-14582)
  * GossiperTest.testHasVersion3Nodes didn't take into account trunk version changes, fixed to rely on latest version (CASSANDRA-16651)
 Merged from 4.0:
+ * Fixed broken classpath when multiple jars in build directory (CASSANDRA-17129)
  * DebuggableThreadPoolExecutor does not propagate client warnings (CASSANDRA-17072)
  * internode_send_buff_size_in_bytes and internode_recv_buff_size_in_bytes have new names. Backward compatibility with the old names added (CASSANDRA-17141)
  * Remove unused configuration parameters from cassandra.yaml (CASSANDRA-17132)
diff --git a/bin/cassandra.in.sh b/bin/cassandra.in.sh
index 5d13cdae70..dcbd12d014 100644
--- a/bin/cassandra.in.sh
+++ b/bin/cassandra.in.sh
@@ -30,10 +30,17 @@ CLASSPATH="$CASSANDRA_CONF"
 # compiled classes. NOTE: This isn't needed by the startup script,
 # it's just used here in constructing the classpath.
 if [ -d $CASSANDRA_HOME/build ] ; then
-    #cassandra_bin="$CASSANDRA_HOME/build/classes/main"
-    cassandra_bin=`ls -1 $CASSANDRA_HOME/build/apache-cassandra*.jar`
+    jars_cnt="`ls -1 $CASSANDRA_HOME/build/apache-cassandra*.jar | grep -v 'javadoc.jar' | grep -v 'sources.jar' | wc -l | xargs echo`"
+    if [ "$jars_cnt" -gt 1 ]; then
+        dir="`cd $CASSANDRA_HOME/build; pwd`"
+        echo "There are JAR artifacts for multiple versions in the $dir directory. Please clean the project with 'ant realclean' and build it again." 1>&2
+        exit 1
+    fi
 
-    CLASSPATH="$CLASSPATH:$cassandra_bin"
+    if [ "$jars_cnt" = "1" ]; then
+        cassandra_bin="`ls -1 $CASSANDRA_HOME/build/apache-cassandra*.jar | grep -v javadoc | grep -v sources`"
+        CLASSPATH="$CLASSPATH:$cassandra_bin"
+    fi
 fi
 
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