diff --git a/approximations/src/main/java/generated/java/lang/StringImpl.java b/approximations/src/main/java/generated/java/lang/StringImpl.java
index 9cafde8..1088863 100644
--- a/approximations/src/main/java/generated/java/lang/StringImpl.java
+++ b/approximations/src/main/java/generated/java/lang/StringImpl.java
@@ -16,7 +16,7 @@ public class StringImpl implements Serializable {
     @java.io.Serial
     private static final long serialVersionUID = -6849794470754667710L;
 
-    private static final int STRING_LENGTH_MAX = 50;
+    private static final int STRING_LENGTH_MAX = 256;
 
     static final byte UTF16 = 1;
 
diff --git a/approximations/src/main/java/generated/java/util/map/ConcurrentHashMapImpl.java b/approximations/src/main/java/generated/java/util/map/ConcurrentHashMapImpl.java
index a2c3575..c889c87 100644
--- a/approximations/src/main/java/generated/java/util/map/ConcurrentHashMapImpl.java
+++ b/approximations/src/main/java/generated/java/util/map/ConcurrentHashMapImpl.java
@@ -47,6 +47,11 @@ public ConcurrentHashMapImpl(int initialCapacity, float loadFactor) {
         super(true, initialCapacity, loadFactor);
     }
 
+    @SuppressWarnings("unused")
+    public ConcurrentHashMapImpl(int initialCapacity, float loadFactor, int concurrencyLevel) {
+        super(true, initialCapacity, loadFactor);
+    }
+
     public LibSLRuntime.Map<K, Map.Entry<K, V>> _getStorage() {
         LibSLRuntime.Map<K, Map.Entry<K, V>> result = this.storage;
         Engine.assume(result != null);