diff --git a/logging-modules/logback/src/main/java/com/baeldung/logback/MapAppender.java b/logging-modules/logback/src/main/java/com/baeldung/logback/MapAppender.java
index 99cc6488e5..a25c54b96e 100644
--- a/logging-modules/logback/src/main/java/com/baeldung/logback/MapAppender.java
+++ b/logging-modules/logback/src/main/java/com/baeldung/logback/MapAppender.java
@@ -3,12 +3,14 @@ package com.baeldung.logback;
 import ch.qos.logback.classic.spi.ILoggingEvent;
 import ch.qos.logback.core.AppenderBase;
 
-import java.util.HashMap;
 import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
 
 public class MapAppender extends AppenderBase<ILoggingEvent> {
 
-    private final Map<String, ILoggingEvent> eventMap = new HashMap<>();
+    private final ConcurrentMap<String, ILoggingEvent> eventMap
+      = new ConcurrentHashMap<>();
 
     private String prefix;