diff --git a/HISTORY.md b/HISTORY.md
index 93d28d2633..0f0b3031af 100644
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -10,7 +10,7 @@
   
   * Add `IsTerminal()` method to the pendulum environment. Action struct in
     continuous RL environments now stores the action as a `double` instead
-    of `double[1]` (#1941, #1931)
+    of `double[1]` (#1941, #1931).
 
 ### mlpack 3.1.1
 ###### 2019-05-26