diff --git a/modules/reitit-core/java-src/reitit/Trie.java b/modules/reitit-core/java-src/reitit/Trie.java
index 6a7b6881..dcfecd0e 100644
--- a/modules/reitit-core/java-src/reitit/Trie.java
+++ b/modules/reitit-core/java-src/reitit/Trie.java
@@ -38,8 +38,8 @@ public class Trie {
     return decode(new String(chars, begin, end - begin), hasPercent, hasPlus);
   }
 
-  public static class Match {
-    public IPersistentMap params;
+  public final static class Match {
+    public final IPersistentMap params;
     public final Object data;
 
     public Match(IPersistentMap params, Object data) {
@@ -47,6 +47,10 @@ public class Trie {
       this.data = data;
     }
 
+    Match assoc(Object key, Object value) {
+      return new Match(params.assoc(key, value), data);
+    }
+
     @Override
     public String toString() {
       Map<Object, Object> m = new HashMap<>();
@@ -113,19 +117,16 @@ public class Trie {
   }
 
   static final class DataMatcher implements Matcher {
-
-    private final IPersistentMap params;
-    private final Object data;
+    private final Match match;
 
     DataMatcher(IPersistentMap params, Object data) {
-      this.params = params;
-      this.data = data;
+      this.match = new Match(params, data);
     }
 
     @Override
     public Match match(int i, int max, char[] path) {
       if (i == max) {
-        return new Match(params, data);
+        return match;
       }
       return null;
     }
@@ -142,7 +143,7 @@ public class Trie {
 
     @Override
     public String toString() {
-      return (data != null ? data.toString() : "nil");
+      return (match.data != null ? match.data.toString() : "nil");
     }
   }
 
@@ -177,10 +178,7 @@ public class Trie {
           }
         }
         final Match m = child.match(stop, max, path);
-        if (m != null) {
-          m.params = m.params.assoc(key, decode(new String(path, i, stop - i), hasPercent, hasPlus));
-        }
-        return m;
+        return m != null ? m.assoc(key, decode(new String(path, i, stop - i), hasPercent, hasPlus)) : null;
       }
       return null;
     }
@@ -219,7 +217,7 @@ public class Trie {
     @Override
     public Match match(int i, int max, char[] path) {
       if (i <= max) {
-        return new Match(params.assoc(parameter, decode(path, i, max)), data);
+        return new Match(params, data).assoc(parameter, decode(path, i, max));
       }
       return null;
     }