diff --git a/src/changes/changes.xml b/src/changes/changes.xml
index 180cc9ae0..905a7b299 100644
--- a/src/changes/changes.xml
+++ b/src/changes/changes.xml
@@ -55,6 +55,7 @@ The <action> type attribute can be add,update,fix,remove.
     <action issue="LANG-1470" type="add" dev="ggregory">Add ArrayUtils.addFirst() methods.</action>
     <action issue="LANG-1437" type="update" dev="ggregory" due-to="Andrei Troie">Remove redundant if statements in join methods #411.</action>
     <action issue="LANG-1460" type="fix" dev="kinow" due-to="Larry West">Trivial: year of release for 3.9 says 2018, should be 2019</action>
+    <action issue="LANG-1476" type="fix" dev="kinow" due-to="emopers">Use synchronise on a set created with Collections.synchronizedSet before iterating</action>
   </release>
 
   <release version="3.9" date="2019-04-09" description="New features and bug fixes. Requires Java 8, supports Java 9, 10, 11">
diff --git a/src/main/java/org/apache/commons/lang3/CharSet.java b/src/main/java/org/apache/commons/lang3/CharSet.java
index 21e7e175f..3fdfd07d8 100644
--- a/src/main/java/org/apache/commons/lang3/CharSet.java
+++ b/src/main/java/org/apache/commons/lang3/CharSet.java
@@ -237,9 +237,11 @@ protected void add(final String str) {
      * @return {@code true} if the set contains the characters
      */
     public boolean contains(final char ch) {
-        for (final CharRange range : set) {
-            if (range.contains(ch)) {
-                return true;
+        synchronized(set) {
+            for (final CharRange range : set) {
+                if (range.contains(ch)) {
+                    return true;
+                }
             }
         }
         return false;