diff --git a/lib/hd/mnemonic.js b/lib/hd/mnemonic.js
index b2ce5099..5edd0538 100644
--- a/lib/hd/mnemonic.js
+++ b/lib/hd/mnemonic.js
@@ -230,15 +230,14 @@ Mnemonic.prototype.getPhrase = function getPhrase() {
  */
 
 Mnemonic.prototype.fromPhrase = function fromPhrase(phrase) {
-  let bits, ent, entropy, lang;
-  let chk, wordlist, cbits, cbytes, words;
+  let words = phrase.split(/[ \u3000]+/);
+  let bits = words.length * 11;
+  let cbits = bits % 32;
+  let cbytes = Math.ceil(cbits / 8);
+  let lang = Mnemonic.getLanguage(words[0]);
+  let wordlist = Mnemonic.getWordlist(lang);
+  let ent, entropy, chk;
 
-  assert(typeof phrase === 'string');
-
-  words = phrase.split(/[ \u3000]+/);
-  bits = words.length * 11;
-  cbits = bits % 32;
-  cbytes = Math.ceil(cbits / 8);
   bits -= cbits;
 
   assert(bits >= common.MIN_ENTROPY);
@@ -249,9 +248,7 @@ Mnemonic.prototype.fromPhrase = function fromPhrase(phrase) {
   ent = Buffer.allocUnsafe(Math.ceil((bits + cbits) / 8));
   ent.fill(0);
 
-  lang = Mnemonic.getLanguage(words[0]);
-  wordlist = Mnemonic.getWordlist(lang);
-
+  // Rebuild entropy bytes.
   for (let i = 0; i < words.length; i++) {
     let word = words[i];
     let index = util.binarySearch(wordlist, word, util.strcmp);
@@ -263,8 +260,8 @@ Mnemonic.prototype.fromPhrase = function fromPhrase(phrase) {
       let pos = i * 11 + j;
       let bit = pos % 8;
       let oct = (pos - bit) / 8;
-      let b = (index >>> (10 - j)) & 1;
-      ent[oct] |= b << (7 - bit);
+      let val = (index >>> (10 - j)) & 1;
+      ent[oct] |= val << (7 - bit);
     }
   }
 
@@ -272,12 +269,13 @@ Mnemonic.prototype.fromPhrase = function fromPhrase(phrase) {
   ent = ent.slice(ent.length - cbytes);
   chk = digest.sha256(entropy);
 
+  // Verify checksum.
   for (let i = 0; i < cbits; i++) {
     let bit = i % 8;
     let oct = (i - bit) / 8;
-    let b = (ent[oct] >>> (7 - bit)) & 1;
-    let j = (chk[oct] >>> (7 - bit)) & 1;
-    if (b !== j)
+    let a = (ent[oct] >>> (7 - bit)) & 1;
+    let b = (chk[oct] >>> (7 - bit)) & 1;
+    if (a !== b)
       throw new Error('Invalid checksum.');
   }