diff --git a/source/ow.ts b/source/ow.ts
index e50827d..ae44740 100644
--- a/source/ow.ts
+++ b/source/ow.ts
@@ -10,16 +10,19 @@ export interface Ow {
 	string: StringPredicate;
 }
 
-export const ow: Ow = Object.assign(
-	(value: any, predicate: Predicate) => {
-		for (const { validator, message } of predicate[validatorSymbol]) {
-			if (!validator(value)) {
-				// TODO: Modify the stack output to show the original `ow()` call instead of this `throw` statement
-				throw new ArgumentError(message(value), ow);
-			}
+const main = (value: any, predicate: Predicate) => {
+	for (const { validator, message } of predicate[validatorSymbol]) {
+		if (!validator(value)) {
+			// TODO: Modify the stack output to show the original `ow()` call instead of this `throw` statement
+			throw new ArgumentError(message(value), main);
 		}
-	},
-	{
-		string: new StringPredicate()
 	}
-);
+};
+
+Object.defineProperties(main, {
+	string: {
+		get: () => new StringPredicate()
+	}
+});
+
+export const ow = main as Ow;