diff --git a/net/picotls/Portfile b/net/picotls/Portfile
index a4c7ba3817d5d..af297c9ec352a 100644
--- a/net/picotls/Portfile
+++ b/net/picotls/Portfile
@@ -10,8 +10,8 @@ PortGroup           openssl 1.0
 # Need O_CLOEXEC
 legacysupport.newest_darwin_requires_legacy 10
 
-github.setup        h2o picotls 703553c94048ba22987e8529590f4c060c0407f8
-version             2024.03.05
+github.setup        h2o picotls 9de892ccf7b1d3dc9467ef92ba9314c155928037
+version             2024.04.08
 revision            0
 categories          net security
 license             MIT
@@ -23,19 +23,19 @@ long_description    {*}${description}. &{name} is designed to be fast, tiny and
 
 github.tarball_from archive
 
-set picotest_hash   6906d90b39684b8b2c18db5b0c7412128140655d
+set picotest_hash   a99858e0c33b97b24cd09ceae729f2be33ec01e1
 
 master_sites-append https://github.com/h2o/picotest/archive/${picotest_hash}/:picotest
 distfiles-append    picotest-${picotest_hash}.tar.gz:picotest
 
 checksums           ${distname}${extract.suffix} \
-                    rmd160  a0461de42f2e24063ce2ab3719782860ad0ec2eb \
-                    sha256  01debc1ebd6dabe301cdf82d7f0d8bf7107f915d3ab48ee26d82f288c66d9d8b \
-                    size    641429 \
+                    rmd160  41d1f9c9d28b8c46076defec7ce89ee36b4dcf0d \
+                    sha256  86b17f4b1a750125488c0e16a1879ee2d60446c32dec5cf2a830887a09bc4e12 \
+                    size    645031 \
                     picotest-${picotest_hash}.tar.gz \
-                    rmd160  934cb89c1683095b5950ece003c5a307c773b058 \
-                    sha256  a297cfd0db85186813622ebffcd8d86d73cd0e590f5fb7fe82ec7d40c88d3677 \
-                    size    1748
+                    rmd160  d0305fe488de16cd68e2919643f4fc9cf60c9025 \
+                    sha256  f3c42d988c8cd1af24dee2e66ce832f3e257bb7766e34167499954c1604c82c0 \
+                    size    1828
 
 extract.only        ${distname}${extract.suffix}
 
@@ -57,6 +57,7 @@ configure.args-append \
 # https://github.com/h2o/picotls/issues/505
 compiler.blacklist-append \
                     *gcc-4.* {clang < 500}
+compiler.c_standard 1999
 
 # FIXME: fails to build with clang on 10.6–10.7:
 # error: call to undeclared library function 'aligned_alloc'