diff --git a/pkgs/quicly/default.nix b/pkgs/quicly/default.nix
index 18e6b4b..cf6af1c 100644
--- a/pkgs/quicly/default.nix
+++ b/pkgs/quicly/default.nix
@@ -65,7 +65,8 @@ stdenv.mkDerivation rec {
     install -Dt $out/lib *.a
     install -Dt $dev/include ../include/quicly.h
     install -Dt $dev/include/quicly ../include/quicly/*.h
-    install -Dt $dev/include/quicly ${picotls}/include/picotls.h
+    install -Dt $dev/include ${picotls}/include/picotls.h
+    install -Dt $dev/include/picotls ${picotls}/include/picotls/*.h
 
     runHook postInstall
   '';