diff --git a/src/Facebook/InstantArticles/Transformer/Getters/ConstantGetter.php b/src/Facebook/InstantArticles/Transformer/Getters/ConstantGetter.php
index 9e2d0824..76d40c9d 100644
--- a/src/Facebook/InstantArticles/Transformer/Getters/ConstantGetter.php
+++ b/src/Facebook/InstantArticles/Transformer/Getters/ConstantGetter.php
@@ -29,7 +29,10 @@ public function createFrom($properties)
      */
     public function withValue($value)
     {
-        Type::enforce($value, Type::STRING);
+        Type::enforce($value, [
+            Type::STRING,
+            Type::INTEGER,
+        ]);
         $this->value = $value;
 
         return $this;