diff --git a/num2words/base.py b/num2words/base.py
index 61b81b0..3b990e3 100644
--- a/num2words/base.py
+++ b/num2words/base.py
@@ -195,9 +195,6 @@ class Num2Word_Base(object):
         if not abs(value) == value:
             raise TypeError(self.errmsg_negord % value)
 
-    def set_wordnums(self):
-        pass
-
     def to_ordinal(self, value):
         return self.to_cardinal(value)
 
diff --git a/tests/test_base.py b/tests/test_base.py
new file mode 100644
index 0000000..7cdc1ee
--- /dev/null
+++ b/tests/test_base.py
@@ -0,0 +1,17 @@
+from __future__ import unicode_literals
+
+from decimal import Decimal
+from unittest import TestCase
+
+from num2words.base import Num2Word_Base
+
+
+class Num2WordBaseTest(TestCase):
+    @classmethod
+    def setUpClass(cls):
+        super(Num2WordBaseTest, cls).setUpClass()
+        cls.base = Num2Word_Base()
+
+    def test_to_currency_not_implemented(self):
+        with self.assertRaises(NotImplementedError):
+            self.base.to_currency(Decimal('1.00'), currency='EUR')