diff --git a/docs/content/tools/cluster.rst b/docs/content/tools/cluster.rst
index 0ab1fd7e0841660b31ad1af94ece0f84b20faec9..9f4f6f370f5d4951976d247a6f4f0fe618bf54be 100644
--- a/docs/content/tools/cluster.rst
+++ b/docs/content/tools/cluster.rst
@@ -19,7 +19,7 @@ a single interval file are combined.
 .. note::
 
     ``bedtools cluster`` requires that you presort your data by chromosome and
-    then by start position (e.g., ``sort k1,1 -k2,2n in.bed > in.sorted.bed``
+    then by start position (e.g., ``sort -k1,1 -k2,2n in.bed > in.sorted.bed``
     for BED files).
     
 .. seealso::