diff --git a/src/main/java/com/annimon/ownlang/lib/NumberValue.java b/src/main/java/com/annimon/ownlang/lib/NumberValue.java
index d92714e..0054281 100644
--- a/src/main/java/com/annimon/ownlang/lib/NumberValue.java
+++ b/src/main/java/com/annimon/ownlang/lib/NumberValue.java
@@ -41,7 +41,7 @@ public final class NumberValue implements Value {
     
     private final Number value;
     
-    public NumberValue(Number value) {
+    private NumberValue(Number value) {
         this.value = value;
     }