diff --git a/transpiler/src/main/java/org/jsweet/transpiler/extension/RemoveJavaDependenciesAdapter.java b/transpiler/src/main/java/org/jsweet/transpiler/extension/RemoveJavaDependenciesAdapter.java
index 02ae0c55..00a61619 100644
--- a/transpiler/src/main/java/org/jsweet/transpiler/extension/RemoveJavaDependenciesAdapter.java
+++ b/transpiler/src/main/java/org/jsweet/transpiler/extension/RemoveJavaDependenciesAdapter.java
@@ -67,6 +67,7 @@ import javax.lang.model.type.ArrayType;
 import javax.lang.model.type.DeclaredType;
 import javax.lang.model.type.TypeMirror;
 
+import com.sun.tools.javac.code.Type;
 import org.jsweet.transpiler.JSweetContext;
 import org.jsweet.transpiler.Java2TypeScriptTranslator;
 import org.jsweet.transpiler.ModuleKind;
@@ -1423,6 +1424,9 @@ public class RemoveJavaDependenciesAdapter extends Java2TypeScriptAdapter {
 			printMacroName(targetMethodName);
 			print(invocation.getTargetExpression());
 			return true;
+		case "valueOf":
+			print(invocation.getArgument(0));
+			return true;
 		}
 
 		return false;
@@ -1496,7 +1500,13 @@ public class RemoveJavaDependenciesAdapter extends Java2TypeScriptAdapter {
 		case "java.lang.Float":
 		case "java.long.Short":
 		case "java.util.Byte":
-			print("new Number(").print(newClass.getArgument(0)).print(").valueOf()");
+		    String argType = newClass.getArgument(0).getType().toString();
+			boolean isCharArgument = Character.class.getName().equals(argType) || "char".equals(argType);
+			if (isCharArgument) {
+				print("new Number(").print(newClass.getArgument(0)).print(".charCodeAt(0)" + ").valueOf()");
+			} else {
+				print("new Number(").print(newClass.getArgument(0)).print(").valueOf()");
+			}
 			substitute = true;
 			break;
 		case "java.util.ArrayList":
@@ -1526,7 +1536,11 @@ public class RemoveJavaDependenciesAdapter extends Java2TypeScriptAdapter {
 		case "java.util.Hashtable":
 		case "java.util.WeakHashMap":
 		case "java.util.LinkedHashMap":
-			if (newClass.getArgumentCount() == 0) {
+			if (newClass.getArgumentCount() == 0 ||
+                !(newClass.getArgument(0).getType() instanceof Type.ClassType) ||
+				!Util.isDeclarationOrSubClassDeclaration(
+                	types(), (Type.ClassType) newClass.getArgument(0).getType(), Map.class.getName())
+			) {
 				print("{}");
 			} else {
 				if (((DeclaredType) newClass.getType()).getTypeArguments().size() == 2 && types().isSameType(
diff --git a/transpiler/src/test/java/source/nativestructures/Maps.java b/transpiler/src/test/java/source/nativestructures/Maps.java
index cc218005..be5d10c8 100644
--- a/transpiler/src/test/java/source/nativestructures/Maps.java
+++ b/transpiler/src/test/java/source/nativestructures/Maps.java
@@ -2,7 +2,9 @@ package source.nativestructures;
 
 import static jsweet.util.Lang.$export;
 
+import java.util.Arrays;
 import java.util.Collections;
+import java.util.Comparator;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -118,7 +120,20 @@ public class Maps {
 		assert m8.containsKey(3);
 		assert m7.containsKey(1);
 		assert !m7.containsKey(3);
-		
+
+		for (Map<String, Integer> map : Arrays.<Map<String, Integer>>asList(
+				new HashMap<>(10),
+                new HashMap<>(10, 11),
+				new TreeMap<>(Comparator.comparingInt(String::hashCode))
+		)) {
+			map.put("a", 1);
+			map.put("b", 2);
+			assert map.size() == 2;
+			assert map.get("a") == 1;
+			assert map.get("b") == 2;
+			assert map.get("c") == null;
+		}
+
 		$export("trace", trace.join(","));
 
 	}
diff --git a/transpiler/src/test/java/source/nativestructures/Numbers.java b/transpiler/src/test/java/source/nativestructures/Numbers.java
index 174bf4ce..26aa7625 100644
--- a/transpiler/src/test/java/source/nativestructures/Numbers.java
+++ b/transpiler/src/test/java/source/nativestructures/Numbers.java
@@ -14,12 +14,33 @@ public class Numbers {
 		boolean knowPages = true;
 		int pageMax = 1;
 		trace.push(Integer.toString(knowPages ? pageMax : 0));
-		$export("trace", trace.join(","));
+
+		Integer i1 = new Integer(Character.valueOf(' '));
+		Integer i2 = new Integer('x');
+		Integer i3 = new Integer("12");
+		assert i1.intValue() == 32;
+		assert i2.intValue() == 120;
+		assert i3.intValue() == 12;
+
+		Long l1 = new Long(Character.valueOf(' '));
+		Long l2 = new Long('x');
+		Long l3 = new Long("12");
+		assert l1.intValue() == 32;
+		assert l2.intValue() == 120;
+		assert l3.intValue() == 12;
+
+		Double d1 = new Double("2.30");
+		assert d1.doubleValue() == 2.30;
+		Double d2 = new Double(2.31);
+		assert d2.doubleValue() == 2.31;
+
 		Double.valueOf("1.2");
 		assert isNaN(Double.NaN);
 		assert isNaN(Float.NaN);
 		assert 1 != Double.NaN;
 		assert 2 != Float.NaN;
+
+		$export("trace", trace.join(","));
 	}
 
 }