diff --git a/coinbase/__init__.py b/coinbase/__init__.py
index ac1c390..270447f 100644
--- a/coinbase/__init__.py
+++ b/coinbase/__init__.py
@@ -476,6 +476,7 @@ def create_button(self, name,
                 "price": str(price),
                 "price_string": str(price),
                 "currency": currency,
+                "price_currency_iso": currency,
                 "type": type,
                 "style": style,
                 "text": text,