diff --git a/src/main/java/com/annimon/ownlang/lib/ValueUtils.java b/src/main/java/com/annimon/ownlang/lib/ValueUtils.java
index 016315c..ef379a6 100644
--- a/src/main/java/com/annimon/ownlang/lib/ValueUtils.java
+++ b/src/main/java/com/annimon/ownlang/lib/ValueUtils.java
@@ -1,133 +1,133 @@
-package com.annimon.ownlang.lib;
-
-import com.annimon.ownlang.exceptions.TypeException;
-import java.lang.reflect.Field;
-import java.lang.reflect.Modifier;
-import java.util.Iterator;
-import java.util.Map;
-import org.json.JSONArray;
-import org.json.JSONObject;
-
-public final class ValueUtils {
-
-    private ValueUtils() { }
-
-    public static Object toObject(Value val) {
-        switch (val.type()) {
-            case Types.ARRAY:
-                return toObject((ArrayValue) val);
-            case Types.MAP:
-                return toObject((MapValue) val);
-            case Types.NUMBER:
-                return val.raw();
-            case Types.STRING:
-                return val.asString();
-            default:
-                return JSONObject.NULL;
-        }
-    }
-
-    public static Object toObject(MapValue map) {
-        final JSONObject result = new JSONObject();
-        for (Map.Entry<Value, Value> entry : map) {
-            final String key = entry.getKey().asString();
-            final Object value = toObject(entry.getValue());
-            result.put(key, value);
-        }
-        return result;
-    }
-
-    public static Object toObject(ArrayValue array) {
-        final JSONArray result = new JSONArray();
-        for (Value value : array) {
-            result.put(toObject(value));
-        }
-        return result;
-    }
-
-    public static Value toValue(Object obj) {
-        if (obj instanceof JSONObject) {
-            return toValue((JSONObject) obj);
-        }
-        if (obj instanceof JSONArray) {
-            return toValue((JSONArray) obj);
-        }
-        if (obj instanceof String) {
-            return new StringValue((String) obj);
-        }
-        if (obj instanceof Number) {
-            return NumberValue.of(((Number) obj));
-        }
-        if (obj instanceof Boolean) {
-            return NumberValue.fromBoolean((Boolean) obj);
-        }
-        // NULL or other
-        return NumberValue.ZERO;
-    }
-
-    public static MapValue toValue(JSONObject json) {
-        final MapValue result = new MapValue(json.length());
-        final Iterator<String> it = json.keys();
-        while(it.hasNext()) {
-            final String key = it.next();
-            final Value value = toValue(json.get(key));
-            result.set(new StringValue(key), value);
-        }
-        return result;
-    }
-
-    public static ArrayValue toValue(JSONArray json) {
-        final int length = json.length();
-        final ArrayValue result = new ArrayValue(length);
-        for (int i = 0; i < length; i++) {
-            final Value value = toValue(json.get(i));
-            result.set(i, value);
-        }
-        return result;
-    }
-
-    public static Number getNumber(Value value) {
-        if (value.type() == Types.NUMBER) return ((NumberValue) value).raw();
-        return value.asInt();
-    }
-
-    public static float getFloatNumber(Value value) {
-        if (value.type() == Types.NUMBER) return ((NumberValue) value).raw().floatValue();
-        return (float) value.asNumber();
-    }
-
-    public static byte[] toByteArray(ArrayValue array) {
-        final int size = array.size();
-        final byte[] result = new byte[size];
-        for (int i = 0; i < size; i++) {
-            result[i] = (byte) array.get(i).asInt();
-        }
-        return result;
-    }
-
-    public static Function consumeFunction(Value value, int argumentNumber) {
-        return consumeFunction(value, " at argument " + (argumentNumber + 1));
-    }
-
-    public static Function consumeFunction(Value value, String errorMessage) {
-        final int type = value.type();
-        if (type != Types.FUNCTION) {
-            throw new TypeException("Function expected" + errorMessage
-                    + ", but found " + Types.typeToString(type));
-        }
-        return ((FunctionValue) value).getValue();
-    }
-
-    public static <T extends Number> MapValue collectNumberConstants(Class<?> clazz, Class<T> type) {
-        MapValue result = new MapValue(20);
-        for (Field field : clazz.getDeclaredFields()) {
-            if (!Modifier.isStatic(field.getModifiers())) continue;
-            if (!field.getType().equals(type)) continue;
-            try {
-                result.set(field.getName(), NumberValue.of((T) field.get(type)));
-            } catch (IllegalAccessException ignore) {
-            }
-        }
-        return result;
-    }
-}
+package com.annimon.ownlang.lib;
+
+import com.annimon.ownlang.exceptions.TypeException;
+import java.lang.reflect.Field;
+import java.lang.reflect.Modifier;
+import java.util.Iterator;
+import java.util.Map;
+import org.json.JSONArray;
+import org.json.JSONObject;
+
+public final class ValueUtils {
+
+    private ValueUtils() { }
+
+    public static Object toObject(Value val) {
+        switch (val.type()) {
+            case Types.ARRAY:
+                return toObject((ArrayValue) val);
+            case Types.MAP:
+                return toObject((MapValue) val);
+            case Types.NUMBER:
+                return val.raw();
+            case Types.STRING:
+                return val.asString();
+            default:
+                return JSONObject.NULL;
+        }
+    }
+
+    public static JSONObject toObject(MapValue map) {
+        final JSONObject result = new JSONObject();
+        for (Map.Entry<Value, Value> entry : map) {
+            final String key = entry.getKey().asString();
+            final Object value = toObject(entry.getValue());
+            result.put(key, value);
+        }
+        return result;
+    }
+
+    public static JSONArray toObject(ArrayValue array) {
+        final JSONArray result = new JSONArray();
+        for (Value value : array) {
+            result.put(toObject(value));
+        }
+        return result;
+    }
+
+    public static Value toValue(Object obj) {
+        if (obj instanceof JSONObject) {
+            return toValue((JSONObject) obj);
+        }
+        if (obj instanceof JSONArray) {
+            return toValue((JSONArray) obj);
+        }
+        if (obj instanceof String) {
+            return new StringValue((String) obj);
+        }
+        if (obj instanceof Number) {
+            return NumberValue.of(((Number) obj));
+        }
+        if (obj instanceof Boolean) {
+            return NumberValue.fromBoolean((Boolean) obj);
+        }
+        // NULL or other
+        return NumberValue.ZERO;
+    }
+
+    public static MapValue toValue(JSONObject json) {
+        final MapValue result = new MapValue(json.length());
+        final Iterator<String> it = json.keys();
+        while(it.hasNext()) {
+            final String key = it.next();
+            final Value value = toValue(json.get(key));
+            result.set(new StringValue(key), value);
+        }
+        return result;
+    }
+
+    public static ArrayValue toValue(JSONArray json) {
+        final int length = json.length();
+        final ArrayValue result = new ArrayValue(length);
+        for (int i = 0; i < length; i++) {
+            final Value value = toValue(json.get(i));
+            result.set(i, value);
+        }
+        return result;
+    }
+
+    public static Number getNumber(Value value) {
+        if (value.type() == Types.NUMBER) return ((NumberValue) value).raw();
+        return value.asInt();
+    }
+
+    public static float getFloatNumber(Value value) {
+        if (value.type() == Types.NUMBER) return ((NumberValue) value).raw().floatValue();
+        return (float) value.asNumber();
+    }
+
+    public static byte[] toByteArray(ArrayValue array) {
+        final int size = array.size();
+        final byte[] result = new byte[size];
+        for (int i = 0; i < size; i++) {
+            result[i] = (byte) array.get(i).asInt();
+        }
+        return result;
+    }
+
+    public static Function consumeFunction(Value value, int argumentNumber) {
+        return consumeFunction(value, " at argument " + (argumentNumber + 1));
+    }
+
+    public static Function consumeFunction(Value value, String errorMessage) {
+        final int type = value.type();
+        if (type != Types.FUNCTION) {
+            throw new TypeException("Function expected" + errorMessage
+                    + ", but found " + Types.typeToString(type));
+        }
+        return ((FunctionValue) value).getValue();
+    }
+
+    public static <T extends Number> MapValue collectNumberConstants(Class<?> clazz, Class<T> type) {
+        MapValue result = new MapValue(20);
+        for (Field field : clazz.getDeclaredFields()) {
+            if (!Modifier.isStatic(field.getModifiers())) continue;
+            if (!field.getType().equals(type)) continue;
+            try {
+                result.set(field.getName(), NumberValue.of((T) field.get(type)));
+            } catch (IllegalAccessException ignore) {
+            }
+        }
+        return result;
+    }
+}
diff --git a/src/main/java/com/annimon/ownlang/modules/json/json_encode.java b/src/main/java/com/annimon/ownlang/modules/json/json_encode.java
index 7222124..a7b4e64 100644
--- a/src/main/java/com/annimon/ownlang/modules/json/json_encode.java
+++ b/src/main/java/com/annimon/ownlang/modules/json/json_encode.java
@@ -1,25 +1,57 @@
 package com.annimon.ownlang.modules.json;
 
 import com.annimon.ownlang.lib.Arguments;
+import com.annimon.ownlang.lib.ArrayValue;
 import com.annimon.ownlang.lib.Function;
+import com.annimon.ownlang.lib.MapValue;
 import com.annimon.ownlang.lib.StringValue;
+import com.annimon.ownlang.lib.Types;
 import com.annimon.ownlang.lib.Value;
 import com.annimon.ownlang.lib.ValueUtils;
 import org.json.JSONException;
 import org.json.JSONObject;
+import org.json.JSONWriter;
 
 
 public final class json_encode implements Function {
 
     @Override
-    public Value execute(Value... args) {
-        Arguments.check(1, args.length);
+    public Value execute(Value[] args) {
+        Arguments.checkOrOr(1, 2, args.length);
         try {
-            final Object root = ValueUtils.toObject(args[0]);
-            final String jsonRaw = JSONObject.valueToString(root);
+            final int indent;
+            if (args.length == 2) {
+                indent = args[1].asInt();
+            } else {
+                indent = 0;
+            }
+
+            final String jsonRaw;
+            if (indent > 0) {
+                jsonRaw = format(args[0], indent);
+            } else {
+                final Object root = ValueUtils.toObject(args[0]);
+                jsonRaw = JSONWriter.valueToString(root);
+            }
             return new StringValue(jsonRaw);
+
         } catch (JSONException ex) {
             throw new RuntimeException("Error while creating json", ex);
         }
     }
+
+    private String format(Value val, int indent) {
+        switch (val.type()) {
+            case Types.ARRAY:
+                return ValueUtils.toObject((ArrayValue) val).toString(indent);
+            case Types.MAP:
+                return ValueUtils.toObject((MapValue) val).toString(indent);
+            case Types.NUMBER:
+                return JSONWriter.valueToString(val.raw());
+            case Types.STRING:
+                return JSONWriter.valueToString(val.asString());
+            default:
+                return JSONWriter.valueToString(JSONObject.NULL);
+        }
+    }
 }
\ No newline at end of file