diff --git a/conf/cassandra.yaml b/conf/cassandra.yaml
index c4732db6fa..543ad65477 100644
--- a/conf/cassandra.yaml
+++ b/conf/cassandra.yaml
@@ -381,12 +381,15 @@ in_memory_compaction_limit_in_mb: 64
 # Uncomment to make compaction mono-threaded, the pre-0.8 default.
 #concurrent_compactors: 1
 
-# Multi-threaded compaction. When enabled, each compaction will use
-# up to one thread per core, plus one thread per sstable being merged.
-# This is usually only useful for SSD-based hardware: otherwise, 
-# your concern is usually to get compaction to do LESS i/o (see:
-# compaction_throughput_mb_per_sec), not more.
-multithreaded_compaction: false
+# multithreaded_compaction: false. When enabled, each compaction will
+# use up to one thread per core, plus one thread per sstable being
+# merged.  This is usually only useful for SSD-based hardware:
+# otherwise, your concern is usually to get compaction to do LESS i/o
+# (see: compaction_throughput_mb_per_sec), not more.
+#
+# WARNING: this setting has caused compaction deadlocks for multiple
+# users (see CASSANDRA-4492).  It is recommended to leave this off
+# unless you are prepared to help troubleshoot.
 
 # Throttles compaction to the given total throughput across the entire
 # system. The faster you insert data, the faster you need to compact in