diff --git a/Changes b/Changes
index a208692930..fb187f44ea 100644
--- a/Changes
+++ b/Changes
@@ -1,6 +1,7 @@
 
 7.18  2017-01-11
   - Fixed support for relative %INC paths in Mojo::Home.
+  - Fixed a bug in Mojo::URL where invalid fragment strings could be generated.
 
 7.17  2017-01-11
   - Fixed Windows bugs in Mojo::File. (kmx)
diff --git a/lib/Mojo/URL.pm b/lib/Mojo/URL.pm
index 85030cd9d4..8d91cf6d46 100644
--- a/lib/Mojo/URL.pm
+++ b/lib/Mojo/URL.pm
@@ -166,7 +166,7 @@ sub to_string {
   # Fragment
   return $url unless defined(my $fragment = $self->fragment);
   return $url . '#' . url_escape encode('UTF-8', $fragment),
-    '^A-Za-z0-9\-._~!$&\'()*+,;=%:@/?';
+    '^A-Za-z0-9\-._~!$&\'()*+,;=:@/?';
 }
 
 sub username { (shift->userinfo // '') =~ /^([^:]+)/ ? $1 : undef }
diff --git a/t/mojo/request.t b/t/mojo/request.t
index 98b5504f05..5f510375c8 100644
--- a/t/mojo/request.t
+++ b/t/mojo/request.t
@@ -2098,7 +2098,7 @@ $req->parse("HTTP/1.1\x0d\x0a\x0d\x0a");
 ok $req->is_finished, 'request is finished';
 is $req->method,      'GET', 'right method';
 is $req->version,     '1.1', 'right version';
-is $req->url, "/#09azAZ!\$%&\'()*+,-./:;=?@%5B%5C%5D%5E_%60%7B%7C%7D~%C3%9F",
+is $req->url, "/#09azAZ!\$%25&\'()*+,-./:;=?@%5B%5C%5D%5E_%60%7B%7C%7D~%C3%9F",
   'right URL';
 
 # Abstract methods
diff --git a/t/mojo/url.t b/t/mojo/url.t
index 79735880c4..d22ba60634 100644
--- a/t/mojo/url.t
+++ b/t/mojo/url.t
@@ -26,22 +26,22 @@ is $url->path,       '/x/index.html', 'right path';
 is $url->query,      'monkey=biz&foo=1', 'right query';
 is $url->path_query, '/x/index.html?monkey=biz&foo=1', 'right path and query';
 is $url->fragment,   '/!%?@3', 'right fragment';
-is "$url", 'https://example.com:8080/x/index.html?monkey=biz&foo=1#/!%?@3',
+is "$url", 'https://example.com:8080/x/index.html?monkey=biz&foo=1#/!%25?@3',
   'right format';
 $url->path('/index.xml');
-is "$url", 'https://example.com:8080/index.xml?monkey=biz&foo=1#/!%?@3',
+is "$url", 'https://example.com:8080/index.xml?monkey=biz&foo=1#/!%25?@3',
   'right format';
 
 # Advanced userinfo and fragment roundtrip
 $url = Mojo::URL->new(
-  'ws://AZaz09-._~!$&\'()*+,;=:@localhost#AZaz09-._~!$&\'()*+,;=%:@/?');
-is $url->scheme,   'ws',                          'right scheme';
-is $url->userinfo, 'AZaz09-._~!$&\'()*+,;=:',     'right userinfo';
-is $url->username, 'AZaz09-._~!$&\'()*+,;=',      'right username';
-is $url->password, '',                            'right password';
-is $url->host,     'localhost',                   'right host';
-is $url->fragment, 'AZaz09-._~!$&\'()*+,;=%:@/?', 'right fragment';
-is "$url", 'ws://localhost#AZaz09-._~!$&\'()*+,;=%:@/?', 'right format';
+  'ws://AZaz09-._~!$&\'()*+,;=:@localhost#AZaz09-._~!$&\'()*+,;=:@/?');
+is $url->scheme,   'ws',                         'right scheme';
+is $url->userinfo, 'AZaz09-._~!$&\'()*+,;=:',    'right userinfo';
+is $url->username, 'AZaz09-._~!$&\'()*+,;=',     'right username';
+is $url->password, '',                           'right password';
+is $url->host,     'localhost',                  'right host';
+is $url->fragment, 'AZaz09-._~!$&\'()*+,;=:@/?', 'right fragment';
+is "$url", 'ws://localhost#AZaz09-._~!$&\'()*+,;=:@/?', 'right format';
 
 # Parameters
 $url = Mojo::URL->new(