diff --git a/lib/utils.js b/lib/utils.js
index 78134c6..f7524ce 100644
--- a/lib/utils.js
+++ b/lib/utils.js
@@ -4,7 +4,7 @@ const { HEX } = require('./scopedChars')
 
 function normalizeIPv4 (host) {
   if (findToken(host, '.') < 3) { return { host, isIPV4: false } }
-  const matches = host.match(/^(\b[01]?\d{1,2}|\b2[0-4]\d|\b25[0-5])(\.([01]?\d{1,2}|2[0-4]\d|25[0-5])){3}$/u) || []
+  const matches = host.match(/^(?:(?:25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9][0-9]|[0-9])\.){3}(?:25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9][0-9]|[0-9])$/u) || []
   const [address] = matches
   if (address) {
     return { host: stripLeadingZeros(address, '.'), isIPV4: true }
diff --git a/test/compatibility.test.js b/test/compatibility.test.js
index 73bc65a..0a57b89 100644
--- a/test/compatibility.test.js
+++ b/test/compatibility.test.js
@@ -10,7 +10,7 @@ test('compatibility Parse', (t) => {
     '//www.g.com/error\n/bleh/bleh',
     'https://fastify.org',
     '//10.10.10.10',
-    '//10.10.000.10',
+    // '//10.10.000.10', <-- not a valid URI per URI spec: https://datatracker.ietf.org/doc/html/rfc5954#section-4.1
     '//[2001:db8::7%en0]',
     '//[2001:dbZ::1]:80',
     '//[2001:db8::1]:80',
diff --git a/test/parse.test.js b/test/parse.test.js
index 2fe2133..fe7c44e 100644
--- a/test/parse.test.js
+++ b/test/parse.test.js
@@ -174,12 +174,21 @@ test('URI parse', (t) => {
   t.equal(components.query, undefined, 'query')
   t.equal(components.fragment, undefined, 'fragment')
 
-  // IPv4address with unformated 0
-  components = URI.parse('//10.10.000.10')
+  // IPv4address with unformated 0 stay as-is
+  components = URI.parse('//10.10.000.10') // not valid as per https://datatracker.ietf.org/doc/html/rfc5954#section-4.1
   t.equal(components.error, undefined, 'IPv4address errors')
   t.equal(components.scheme, undefined, 'scheme')
   t.equal(components.userinfo, undefined, 'userinfo')
-  t.equal(components.host, '10.10.0.10', 'host')
+  t.equal(components.host, '10.10.000.10', 'host')
+  t.equal(components.port, undefined, 'port')
+  t.equal(components.path, '', 'path')
+  t.equal(components.query, undefined, 'query')
+  t.equal(components.fragment, undefined, 'fragment')
+  components = URI.parse('//01.01.01.01') // not valid in URIs: https://datatracker.ietf.org/doc/html/rfc3986#section-7.4
+  t.equal(components.error, undefined, 'IPv4address errors')
+  t.equal(components.scheme, undefined, 'scheme')
+  t.equal(components.userinfo, undefined, 'userinfo')
+  t.equal(components.host, '01.01.01.01', 'host')
   t.equal(components.port, undefined, 'port')
   t.equal(components.path, '', 'path')
   t.equal(components.query, undefined, 'query')