diff --git a/src/main/java/com/annimon/ownlang/modules/std/NumberFunctions.java b/src/main/java/com/annimon/ownlang/modules/std/NumberFunctions.java
new file mode 100644
index 0000000..31d2cd6
--- /dev/null
+++ b/src/main/java/com/annimon/ownlang/modules/std/NumberFunctions.java
@@ -0,0 +1,21 @@
+package com.annimon.ownlang.modules.std;
+
+import com.annimon.ownlang.lib.Arguments;
+import com.annimon.ownlang.lib.NumberValue;
+import com.annimon.ownlang.lib.StringValue;
+import com.annimon.ownlang.lib.Types;
+import com.annimon.ownlang.lib.Value;
+
+public final class NumberFunctions {
+
+    public static Value toHexString(Value... args) {
+        Arguments.check(1, args.length);
+        long value;
+        if (args[0].type() == Types.NUMBER) {
+            value = ((NumberValue) args[0]).asLong();
+        } else {
+            value = (long) args[0].asNumber();
+        }
+        return new StringValue(Long.toHexString(value));
+    }
+}
diff --git a/src/main/java/com/annimon/ownlang/modules/std/std.java b/src/main/java/com/annimon/ownlang/modules/std/std.java
index ffce722..a8618db 100644
--- a/src/main/java/com/annimon/ownlang/modules/std/std.java
+++ b/src/main/java/com/annimon/ownlang/modules/std/std.java
@@ -27,6 +27,9 @@ public final class std implements Module {
         Functions.set("sync", new std_sync());
         Functions.set("try", new std_try());
 
+        // Numbers
+        Functions.set("toHexString", NumberFunctions::toHexString);
+
         // String
         Functions.set("sprintf", new std_sprintf());
         Functions.set("split", new std_split());