diff --git a/bipentropy/bipentropy.py b/bipentropy/bipentropy.py
index cf81987..f7c5b27 100644
--- a/bipentropy/bipentropy.py
+++ b/bipentropy/bipentropy.py
@@ -50,9 +50,15 @@ class BIPEntropy(object):
             raise ValueError('ERROR: Invalid xprv')
         return self.__hmac_sha512(self.__derive_k(path, xprv))
 
+    def bip32_xprv_to_hex(self, index, width, xprv_string):
+        # export entropy as hex
+        path = f"83696968p/128169p/{width}p/{index}p"
+        ent = self.bip32_xprv_to_entropy(path, xprv_string)
+        return ent[0:width].hex()
+
     def bip32_xprv_to_xprv(self, index, xprv_string):
         # app_no = 32 => XPRV to XPRV
-        path = "83696968p/32p/{index}p".format(index=index)
+        path = f"83696968p/32p/{index}p"
         node = BTC.parse.bip32_prv(xprv_string).subkey_for_path(path)
 
         # if API to pycoin hadn't been shitcoined:
diff --git a/test_entropy.py b/test_entropy.py
index d62003d..4136745 100644
--- a/test_entropy.py
+++ b/test_entropy.py
@@ -84,7 +84,15 @@ def test_xprv_application():
     result = e.bip32_xprv_to_xprv(0, XPRV)
     assert result == 'xprv9s21ZrQH143K3KJoGoKpsDsWdDNDBKs1wqFymBpCGJtrYXrfKzykGDBadZq5SrNde22F83X9qhFZr4uyV9TptTgLqCBc6XFN9tssphdxVeg'
 
+@pytest.mark.parametrize('index, width, expect', [
+        (0, 32, '4f4ea2ef43af14e51f2453221d50762fc3767e2287dc524ca58f10e5225a6ead'),
+        (0, 64, '4fc6759ef9c0e12aed757ad874706a3955ef125c8f8eabb3909aeda028f5e285bf496a23265bac09f537f4cc5e1efa689f5625ded2cd996c042b2657263c6816'),
+        (1234, 64, 'e1a35aeae27cb3c93b0d437e94b64a891cdff9ac250537ec675d0e6a2680f1d2edf9927f4c5233b19b15fdea4063a8b62f85ff8666176d226741ed192075a8db'),
+    ])
+def test_hex_application(index, width, expect):
+    e = bipentropy.BIPEntropy()
+    assert e.bip32_xprv_to_hex(index, width, XPRV) == expect
+
 if __name__ == "__main__":
     pytest.main()
 
-