diff --git a/lib/http/base.js b/lib/http/base.js
index 4797be1aa..a1dd0e9ac 100644
--- a/lib/http/base.js
+++ b/lib/http/base.js
@@ -892,8 +892,7 @@ HTTPBaseOptions.prototype.fromOptions = function fromOptions(options) {
   }
 
   if (options.port != null) {
-    assert(typeof options.port === 'number', 'Port must be a number.');
-    assert(options.port > 0 && options.port <= 0xffff);
+    assert(util.isU16(options.port), 'Port must be a number.');
     this.port = options.port;
   }
 
diff --git a/lib/http/server.js b/lib/http/server.js
index c8f7b6067..a68cf2522 100644
--- a/lib/http/server.js
+++ b/lib/http/server.js
@@ -766,8 +766,7 @@ HTTPOptions.prototype.fromOptions = function fromOptions(options) {
   }
 
   if (options.port != null) {
-    assert(typeof options.port === 'number', 'Port must be a number.');
-    assert(options.port > 0 && options.port <= 0xffff);
+    assert(util.isU16(options.port), 'Port must be a number.');
     this.port = options.port;
   }
 
diff --git a/lib/net/pool.js b/lib/net/pool.js
index 7859a55ce..cfd923178 100644
--- a/lib/net/pool.js
+++ b/lib/net/pool.js
@@ -3726,8 +3726,7 @@ PoolOptions.prototype.fromOptions = function fromOptions(options) {
   }
 
   if (options.port != null) {
-    assert(typeof options.port === 'number');
-    assert(options.port > 0 && options.port <= 0xffff);
+    assert(util.isU16(options.port));
     this.port = options.port;
     this.publicPort = options.port;
   }
@@ -3738,8 +3737,7 @@ PoolOptions.prototype.fromOptions = function fromOptions(options) {
   }
 
   if (options.publicPort != null) {
-    assert(typeof options.publicPort === 'number');
-    assert(options.publicPort > 0 && options.publicPort <= 0xffff);
+    assert(util.isU16(options.publicPort));
     this.publicPort = options.publicPort;
   }
 
diff --git a/lib/utils/util.js b/lib/utils/util.js
index 5e7e390b3..e7d9288c4 100644
--- a/lib/utils/util.js
+++ b/lib/utils/util.js
@@ -31,154 +31,54 @@ const inspectOptions = {
 };
 
 /**
- * Return hrtime (shim for browser).
- * @param {Array} time
- * @returns {Array}
- */
-
-util.hrtime = function hrtime(time) {
-  if (!process.hrtime) {
-    const now = util.ms();
-
-    if (time) {
-      const [hi, lo] = time;
-      const start = hi * 1000 + lo / 1e6;
-      return now - start;
-    }
-
-    const ms = now % 1000;
-    const sec = (now - ms) / 1000;
-
-    return [sec, ms * 1e6];
-  }
-
-  if (time) {
-    const [hi, lo] = process.hrtime(time);
-    return hi * 1000 + lo / 1e6;
-  }
-
-  return process.hrtime();
-};
-
-/**
- * Test whether a string is base58 (note that you
- * may get a false positive on a hex string).
- * @param {String?} obj
- * @returns {Boolean}
- */
-
-util.isBase58 = function isBase58(obj) {
-  return typeof obj === 'string' && /^[1-9a-zA-Z]+$/.test(obj);
-};
-
-/**
- * Test whether a string is hex (length must be even).
- * Note that this _could_ await a false positive on
- * base58 strings.
- * @param {String?} obj
+ * Test whether a number is Number,
+ * finite, and below MAX_SAFE_INTEGER.
+ * @param {Number?} value
  * @returns {Boolean}
  */
 
-util.isHex = function isHex(obj) {
-  return typeof obj === 'string'
-    && /^[0-9a-f]+$/i.test(obj)
-    && obj.length % 2 === 0;
-};
-
-/**
- * Reverse a hex-string (used because of
- * bitcoind's affinity for uint256le).
- * @param {String} data - Hex string.
- * @returns {String} Reversed hex string.
- */
-
-util.revHex = function revHex(data) {
-  assert(typeof data === 'string');
-  assert(data.length > 0);
-  assert(data.length % 2 === 0);
-
-  let out = '';
-
-  for (let i = 0; i < data.length; i += 2)
-    out = data.slice(i, i + 2) + out;
-
-  return out;
+util.isNumber = function isNumber(value) {
+  return Number.isSafeInteger(value);
 };
 
 /**
- * Test whether the result of a positive
- * addition would be below MAX_SAFE_INTEGER.
- * @param {Number} value
+ * Test whether an object is an int.
+ * @param {Number?} value
  * @returns {Boolean}
  */
 
-util.isSafeAddition = function isSafeAddition(a, b) {
-  // We only work on positive numbers.
-  assert(a >= 0);
-  assert(b >= 0);
-
-  // Fast case.
-  if (a <= 0xfffffffffffff && b <= 0xfffffffffffff)
-    return true;
-
-  // Do a 64 bit addition and check the top 11 bits.
-  let ahi = (a * (1 / 0x100000000)) | 0;
-  const alo = a | 0;
-
-  let bhi = (b * (1 / 0x100000000)) | 0;
-  const blo = b | 0;
-
-  // Credit to @indutny for this method.
-  const lo = (alo + blo) | 0;
-
-  const s = lo >> 31;
-  const as = alo >> 31;
-  const bs = blo >> 31;
-
-  const c = ((as & bs) | (~s & (as ^ bs))) & 1;
-
-  let hi = (((ahi + bhi) | 0) + c) | 0;
-
-  hi >>>= 0;
-  ahi >>>= 0;
-  bhi >>>= 0;
-
-  // Overflow?
-  if (hi < ahi || hi < bhi)
-    return false;
-
-  return (hi & 0xffe00000) === 0;
+util.isInt = function isInt(value) {
+  return util.isNumber(value) && value % 1 === 0;
 };
 
 /**
- * Test whether a number is Number,
- * finite, and below MAX_SAFE_INTEGER.
+ * Test whether an object is an int.
  * @param {Number?} value
  * @returns {Boolean}
  */
 
-util.isNumber = function isNumber(value) {
-  return Number.isSafeInteger(value);
+util.isUint = function isUint(value) {
+  return util.isInt(value) && value >= 0;
 };
 
 /**
- * Test whether an object is an int.
+ * Test whether a number is a float.
  * @param {Number?} value
  * @returns {Boolean}
  */
 
-util.isInt = function isInt(value) {
-  return util.isNumber(value) && value % 1 === 0;
+util.isFloat = function isFloat(value) {
+  return typeof value === 'number' && isFinite(value);
 };
 
 /**
- * Test whether an object is an int.
+ * Test whether a number is a positive float.
  * @param {Number?} value
  * @returns {Boolean}
  */
 
-util.isUint = function isUint(value) {
-  return util.isInt(value) && value >= 0;
+util.isUfloat = function isUfloat(value) {
+  return util.isFloat(value) && value >= 0;
 };
 
 /**
@@ -261,24 +161,109 @@ util.isU64 = function isU64(value) {
   return util.isUint(value);
 };
 
+/**
+ * Test whether a string is a plain
+ * ascii string (no control characters).
+ * @param {String} str
+ * @returns {Boolean}
+ */
+
+util.isAscii = function isAscii(str) {
+  return typeof str === 'string' && /^[\t\n\r -~]*$/.test(str);
+};
+
+/**
+ * Test whether a string is base58 (note that you
+ * may get a false positive on a hex string).
+ * @param {String?} str
+ * @returns {Boolean}
+ */
+
+util.isBase58 = function isBase58(str) {
+  return typeof str === 'string' && /^[1-9a-zA-Z]+$/.test(str);
+};
+
+/**
+ * Test whether a string is hex (length must be even).
+ * Note that this _could_ await a false positive on
+ * base58 strings.
+ * @param {String?} str
+ * @returns {Boolean}
+ */
+
+util.isHex = function isHex(str) {
+  if (typeof str !== 'string')
+    return false;
+  return /^[0-9a-f]+$/i.test(str) && str.length % 2 === 0;
+};
+
 /**
  * Test whether an object is a 160 bit hash (hex string).
- * @param {String?} value
+ * @param {String?} hash
  * @returns {Boolean}
  */
 
 util.isHex160 = function isHex160(hash) {
-  return util.isHex(hash) && hash.length === 40;
+  if (typeof hash !== 'string')
+    return false;
+  return hash.length === 40 && util.isHex(hash);
 };
 
 /**
  * Test whether an object is a 256 bit hash (hex string).
- * @param {String?} value
+ * @param {String?} hash
  * @returns {Boolean}
  */
 
 util.isHex256 = function isHex256(hash) {
-  return util.isHex(hash) && hash.length === 64;
+  if (typeof hash !== 'string')
+    return false;
+  return hash.length === 64 && util.isHex(hash);
+};
+
+/**
+ * Test whether the result of a positive
+ * addition would be below MAX_SAFE_INTEGER.
+ * @param {Number} value
+ * @returns {Boolean}
+ */
+
+util.isSafeAddition = function isSafeAddition(a, b) {
+  // We only work on positive numbers.
+  assert(a >= 0);
+  assert(b >= 0);
+
+  // Fast case.
+  if (a <= 0xfffffffffffff && b <= 0xfffffffffffff)
+    return true;
+
+  // Do a 64 bit addition and check the top 11 bits.
+  let ahi = (a * (1 / 0x100000000)) | 0;
+  const alo = a | 0;
+
+  let bhi = (b * (1 / 0x100000000)) | 0;
+  const blo = b | 0;
+
+  // Credit to @indutny for this method.
+  const lo = (alo + blo) | 0;
+
+  const s = lo >> 31;
+  const as = alo >> 31;
+  const bs = blo >> 31;
+
+  const c = ((as & bs) | (~s & (as ^ bs))) & 1;
+
+  let hi = (((ahi + bhi) | 0) + c) | 0;
+
+  hi >>>= 0;
+  ahi >>>= 0;
+  bhi >>>= 0;
+
+  // Overflow?
+  if (hi < ahi || hi < bhi)
+    return false;
+
+  return (hi & 0xffe00000) === 0;
 };
 
 /**
@@ -367,6 +352,36 @@ util.error = function error(...args) {
   process.stderr.write(msg + '\n');
 };
 
+/**
+ * Return hrtime (shim for browser).
+ * @param {Array} time
+ * @returns {Array}
+ */
+
+util.hrtime = function hrtime(time) {
+  if (!process.hrtime) {
+    const now = util.ms();
+
+    if (time) {
+      const [hi, lo] = time;
+      const start = hi * 1000 + lo / 1e6;
+      return now - start;
+    }
+
+    const ms = now % 1000;
+    const sec = (now - ms) / 1000;
+
+    return [sec, ms * 1e6];
+  }
+
+  if (time) {
+    const [hi, lo] = process.hrtime(time);
+    return hi * 1000 + lo / 1e6;
+  }
+
+  return process.hrtime();
+};
+
 /**
  * Get current time in unix time (seconds).
  * @returns {Number}
@@ -651,6 +666,26 @@ util.hex32 = function hex32(num) {
   throw new Error('Number too big.');
 };
 
+/**
+ * Reverse a hex-string (used because of
+ * bitcoind's affinity for uint256le).
+ * @param {String} data - Hex string.
+ * @returns {String} Reversed hex string.
+ */
+
+util.revHex = function revHex(data) {
+  assert(typeof data === 'string');
+  assert(data.length > 0);
+  assert(data.length % 2 === 0);
+
+  let out = '';
+
+  for (let i = 0; i < data.length; i += 2)
+    out = data.slice(i, i + 2) + out;
+
+  return out;
+};
+
 /**
  * Reverse an object's keys and values.
  * @param {Object} obj
@@ -772,17 +807,6 @@ if (!''.startsWith) {
   };
 }
 
-/**
- * Test whether a string is a plain
- * ascii string (no control characters).
- * @param {String} str
- * @returns {Boolean}
- */
-
-util.isAscii = function isAscii(str) {
-  return /^[\t\n\r -~]*$/.test(str);
-};
-
 /**
  * Get memory usage info.
  * @returns {Object}
diff --git a/lib/wallet/http.js b/lib/wallet/http.js
index 01e95d3bb..0c650b852 100644
--- a/lib/wallet/http.js
+++ b/lib/wallet/http.js
@@ -1016,8 +1016,7 @@ HTTPOptions.prototype.fromOptions = function fromOptions(options) {
   }
 
   if (options.port != null) {
-    assert(typeof options.port === 'number', 'Port must be a number.');
-    assert(options.port > 0 && options.port <= 0xffff);
+    assert(util.isU16(options.port), 'Port must be a number.');
     this.port = options.port;
   }