diff --git a/src/com/annimon/ownlang/lib/Functions.java b/src/com/annimon/ownlang/lib/Functions.java
index dfddc69..48abd11 100644
--- a/src/com/annimon/ownlang/lib/Functions.java
+++ b/src/com/annimon/ownlang/lib/Functions.java
@@ -9,7 +9,6 @@ import java.util.Map;
  */
 public final class Functions {
 
-    private static final NumberValue ZERO = new NumberValue(0);
     private static final Map<String, Function> functions;
     
     static {
@@ -30,7 +29,7 @@ public final class Functions {
             for (Value arg : args) {
                 System.out.println(arg.asString());
             }
-            return ZERO;
+            return NumberValue.ZERO;
         });
     }
     
diff --git a/src/com/annimon/ownlang/lib/NumberValue.java b/src/com/annimon/ownlang/lib/NumberValue.java
index f9e5256..c9d817e 100644
--- a/src/com/annimon/ownlang/lib/NumberValue.java
+++ b/src/com/annimon/ownlang/lib/NumberValue.java
@@ -6,6 +6,8 @@ package com.annimon.ownlang.lib;
  */
 public final class NumberValue implements Value {
     
+    public static final NumberValue ZERO = new NumberValue(0);
+    
     private final double value;
     
     public NumberValue(boolean value) {
diff --git a/src/com/annimon/ownlang/lib/Variables.java b/src/com/annimon/ownlang/lib/Variables.java
index 43f1d72..50d4aa4 100644
--- a/src/com/annimon/ownlang/lib/Variables.java
+++ b/src/com/annimon/ownlang/lib/Variables.java
@@ -9,7 +9,6 @@ import java.util.Map;
  */
 public final class Variables {
 
-    private static final NumberValue ZERO = new NumberValue(0);
     private static final Map<String, Value> variables;
     
     static {
@@ -25,7 +24,7 @@ public final class Variables {
     }
     
     public static Value get(String key) {
-        if (!isExists(key)) return ZERO;
+        if (!isExists(key)) return NumberValue.ZERO;
         return variables.get(key);
     }