diff --git a/faststripe/core.py b/faststripe/core.py
index b6f4c54..a9dc9d6 100644
--- a/faststripe/core.py
+++ b/faststripe/core.py
@@ -12,6 +12,8 @@
 from inspect import Parameter, Signature
 
 import re
+from urllib.parse import quote
+
 
 # %% ../nbs/01_core.ipynb 4
 stripe_api_url = 'https://api.stripe.com'
diff --git a/nbs/01_core.ipynb b/nbs/01_core.ipynb
index ffd08e0..b368c58 100644
--- a/nbs/01_core.ipynb
+++ b/nbs/01_core.ipynb
@@ -33,7 +33,8 @@
     "from faststripe.spec import docs_url\n",
     "from inspect import Parameter, Signature\n",
     "\n",
-    "import re"
+    "import re\n",
+    "from urllib.parse import quote\n"
    ]
   },
   {
@@ -1079,4 +1080,4 @@
  "metadata": {},
  "nbformat": 4,
  "nbformat_minor": 5
-}
+}
\ No newline at end of file