diff --git a/src/main/java/org/typo3/gerrit/plugins/avatars/typo3org/ExternalUrlAvatarProvider.java b/src/main/java/org/typo3/gerrit/plugins/avatars/typo3org/ExternalUrlAvatarProvider.java
index 6545b2b..8f29462 100644
--- a/src/main/java/org/typo3/gerrit/plugins/avatars/typo3org/ExternalUrlAvatarProvider.java
+++ b/src/main/java/org/typo3/gerrit/plugins/avatars/typo3org/ExternalUrlAvatarProvider.java
@@ -29,6 +29,7 @@
 import org.slf4j.LoggerFactory;
 
 import java.io.UnsupportedEncodingException;
+import java.net.URLEncoder;
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
 
@@ -58,6 +59,14 @@
       return null;
     }
 
+    try {
+      username = URLEncoder.encode(username, "UTF-8");
+    } catch (UnsupportedEncodingException e) {
+      Logger log = LoggerFactory.getLogger(ExternalUrlAvatarProvider.class);
+      log.warn("Weird thing, UTF-8 as encoding is not supported");
+      return null;
+    }
+
     if (externalAvatarUrl == null) {
       Logger log = LoggerFactory.getLogger(ExternalUrlAvatarProvider.class);
       log.warn("Avatar URL is not configured, cannot show avatars. Please configure avatar.url in etc/gerrit.config");