Index: /trunk/src/org/openstreetmap/josm/io/CachedFile.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/io/CachedFile.java	(revision 13724)
+++ /trunk/src/org/openstreetmap/josm/io/CachedFile.java	(revision 13725)
@@ -13,4 +13,5 @@
 import java.net.MalformedURLException;
 import java.net.URL;
+import java.net.URLEncoder;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
@@ -489,5 +490,5 @@
                 uc = u.replaceAll("%<(.*)>", "");
             } else {
-                uc = u.replaceAll("%<(.*)>", "$1"+parameter);
+                uc = u.replaceAll("%<(.*)>", "$1"+URLEncoder.encode(parameter, "UTF-8"));
             }
             if (!uc.equals(u))