diff --git a/src/main/java/com/googlesource/gerrit/plugins/avatars/external/ExternalUrlAvatarProvider.java b/src/main/java/com/googlesource/gerrit/plugins/avatars/external/ExternalUrlAvatarProvider.java
index 093aacd..c022427 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/avatars/external/ExternalUrlAvatarProvider.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/avatars/external/ExternalUrlAvatarProvider.java
@@ -33,7 +33,7 @@
 @Singleton
 public class ExternalUrlAvatarProvider implements AvatarProvider {
 
-  private static final String REPLACE_MARKER = "%s";
+  private static final String USER_PLACEHOLDER = "${user}";
 
   private final String pluginName;
   private final boolean ssl;
@@ -63,11 +63,11 @@
     }
 
     // it is unrealistic that all users share the same avatar image, thus we're
-    // warning if we can't find our marker (%s)
-    if (!externalAvatarUrl.contains(REPLACE_MARKER)) {
+    // warning if we can't find our marker
+    if (!externalAvatarUrl.contains(USER_PLACEHOLDER)) {
       Logger log = LoggerFactory.getLogger(ExternalUrlAvatarProvider.class);
       log.warn("Avatar provider url '" + externalAvatarUrl
-          + "' does not contain " + REPLACE_MARKER
+          + "' does not contain " + USER_PLACEHOLDER
           + ", so cannot replace it with username");
       return null;
     }
@@ -94,20 +94,20 @@
   }
 
   /**
-   * Takes #{replacement} and substitutes the marker REPLACE_MARKER in #{url}
+   * Takes #{replacement} and substitutes the marker USER_PLACEHOLDER in #{url}
    * after it has been URL encoded
    *
-   * @param url The URL, usually containing #{REPLACE_MARKER}
+   * @param url The URL, usually containing #{USER_PLACEHOLDER}
    * @param replacement String to be put inside
    * @return new URL
    */
   private String replaceInUrl(String url, String replacement) {
     if (replacement == null || url == null
-        || url.contains(REPLACE_MARKER) == false) {
+        || url.contains(USER_PLACEHOLDER) == false) {
       return url;
     }
 
     // as we can't assume anything of 'replacement', we're URL encoding it
-    return url.replace(REPLACE_MARKER, Url.encode(replacement));
+    return url.replace(USER_PLACEHOLDER, Url.encode(replacement));
   }
 }
diff --git a/src/main/resources/Documentation/config.md b/src/main/resources/Documentation/config.md
index 507c83f..f76d7a9 100644
--- a/src/main/resources/Documentation/config.md
+++ b/src/main/resources/Documentation/config.md
@@ -6,15 +6,15 @@
 
 ```
   [plugin "@PLUGIN@"]
-    url = http://example.org/avatars/%s.jpg
+    url = http://example.org/avatars/${user}.jpg
     changeUrl = http://example.org/account.html
     sizeParameter = s=${size}x${size}
 ```
 
 <a id="url">
 `plugin.@PLUGIN@.url`
-:	The location of avatar images containing `%s`, which will then be
-	replaced by the `username`. Required.
+:	The location of avatar images containing `${user}`, which will then
+	be replaced by the `username`. Required.
 
 <a id="changeUrl">
 `plugin.@PLUGIN@.changeUrl`