diff --git a/doc/api/cluster.md b/doc/api/cluster.md
index 4e2b4eab88..236d461736 100644
--- a/doc/api/cluster.md
+++ b/doc/api/cluster.md
@@ -5,7 +5,7 @@
 > Stability: 2 - Stable
 
 A single instance of Node.js runs in a single thread. To take advantage of
-multi-core systems the user will sometimes want to launch a cluster of Node.js
+multi-core systems, the user will sometimes want to launch a cluster of Node.js
 processes to handle the load.
 
 The cluster module allows easy creation of child processes that all share