diff --git a/src/types.js b/src/types.js
index ab617a8..51165a8 100644
--- a/src/types.js
+++ b/src/types.js
@@ -8,6 +8,7 @@ function UInt31 (value) {
 function BIP32Path (value) {
   return typeforce.String(value) && value.match(/^(m\/)?(\d+'?\/)*\d+'?$/)
 }
+BIP32Path.toJSON = function () { return 'BIP32 derivation path' }
 
 var SATOSHI_MAX = 2.1 * 1e15
 function Satoshi (value) {
diff --git a/test/hdnode.js b/test/hdnode.js
index 37d62a3..2c4383e 100644
--- a/test/hdnode.js
+++ b/test/hdnode.js
@@ -384,7 +384,7 @@ describe('HDNode', function () {
       fixtures.invalid.derivePath.forEach(function (fx) {
         assert.throws(function () {
           master.derivePath(fx)
-        }, /Expected Bip32Path/)
+        }, /Expected BIP32 derivation path/)
       })
     })
   })