lib/PublicInbox/URIimap.pm | 3 +++
 t/uri_imap.t               | 8 ++++++++

diff --git a/lib/PublicInbox/URIimap.pm b/lib/PublicInbox/URIimap.pm
index dc19346815556095f8ae056033f819d20b318905..df9f5fd9ebeff2040066afac23ef0655c362f42c 100644
--- a/lib/PublicInbox/URIimap.pm
+++ b/lib/PublicInbox/URIimap.pm
@@ -30,6 +30,9 @@ 	# no #frag in RFC 5092 from what I can tell
 	my ($scheme, $auth, $path, $query, $_frag) = uri_split($$self);
 	$path =~ s!\A/+!/!; # excessive leading slash
 
+	# upper-case uidvalidity= and uid= parameter names
+	$path =~ s/;([^=]+)=([^;]*)/;\U$1\E=$2/g;
+
 	# lowercase the host portion
 	$auth =~ s#\A(.*@)?(.*?)(?::([0-9]+))?\z#
 		my $ret = ($1//'').lc($2);
diff --git a/t/uri_imap.t b/t/uri_imap.t
index e2aadf8420dccce17f865e54026f4090ac4d34f4..ed24fc1be073af311587bcc2904f4f8fb075290b 100644
--- a/t/uri_imap.t
+++ b/t/uri_imap.t
@@ -79,7 +79,11 @@ is($uri->uidvalidity(2), 2, 'iuid set');
 is($$uri, 'imap://0/mmm;UIDVALIDITY=2', 'uidvalidity appended');
 is($uri->iuid, undef, 'no iuid');
 
+is(PublicInbox::URIimap->new('imap://0/x;uidvalidity=1')->canonical->as_string,
+	'imap://0/x;UIDVALIDITY=1', 'capitalized UIDVALIDITY');
+
 $uri = PublicInbox::URIimap->new('imap://0/mmm/;uid=8');
+is($uri->canonical->as_string, 'imap://0/mmm/;UID=8', 'canonicalized UID');
 is($uri->mailbox, 'mmm', 'mailbox works with iuid');
 is($uri->iuid, 8, 'iuid extracted');
 is($uri->iuid(9), 9, 'iuid set');
@@ -92,5 +96,9 @@ is($$uri, 'imap://0/mmm;UIDVALIDITY=4/;UID=9',
 	'uidvalidity replaced with iuid');
 is($uri->iuid(3), 3, 'iuid set with uidvalidity');
 is($$uri, 'imap://0/mmm;UIDVALIDITY=4/;UID=3', 'iuid replaced properly');
+
+my $lc = lc($$uri);
+is(PublicInbox::URIimap->new($lc)->canonical->as_string, "$$uri",
+	'canonical uppercased both params');
 
 done_testing;