diff --git a/DEPENDENCIES b/DEPENDENCIES
index 70452d7f..07839077 100644
--- a/DEPENDENCIES
+++ b/DEPENDENCIES
@@ -1,4 +1,4 @@
 vendorpull https://github.com/sourcemeta/vendorpull dea311b5bfb53b6926a4140267959ae334d3ecf4
 noa https://github.com/sourcemeta/noa 5ff4024902642afc9cc2f9a9e02ae9dff9d15d4f
 jsontoolkit https://github.com/sourcemeta/jsontoolkit 958d686c4bbcb1f232ed8d313956929e38af84d2
-hydra https://github.com/sourcemeta/hydra d5e0c314dae88b0bf2ac4eeff2c7395910e2c7e9
+hydra https://github.com/sourcemeta/hydra f35845241d8086188a627134142b3e4d8ec23ed4
diff --git a/vendor/hydra/cmake/FindBearSSL.cmake b/vendor/hydra/cmake/FindBearSSL.cmake
index 25c04e8d..f4a1e3a5 100644
--- a/vendor/hydra/cmake/FindBearSSL.cmake
+++ b/vendor/hydra/cmake/FindBearSSL.cmake
@@ -330,31 +330,33 @@ if(NOT BearSSL_FOUND)
       WINDOWS_EXPORT_ALL_SYMBOLS TRUE
       EXPORT_NAME bearssl)
 
-  include(GNUInstallDirs)
-  install(TARGETS bearssl
-    EXPORT bearssl
-    PUBLIC_HEADER DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
-      COMPONENT sourcemeta_hydra_dev
-    PRIVATE_HEADER DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
-      COMPONENT sourcemeta_hydra_dev
-    RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}"
-      COMPONENT sourcemeta_hydra
-    LIBRARY DESTINATION "${CMAKE_INSTALL_LIBDIR}"
-      COMPONENT sourcemeta_hydra
-      NAMELINK_COMPONENT sourcemeta_hydra_dev
-    ARCHIVE DESTINATION "${CMAKE_INSTALL_LIBDIR}"
+  if(HYDRA_INSTALL)
+    include(GNUInstallDirs)
+    install(TARGETS bearssl
+      EXPORT bearssl
+      PUBLIC_HEADER DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
+        COMPONENT sourcemeta_hydra_dev
+      PRIVATE_HEADER DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
+        COMPONENT sourcemeta_hydra_dev
+      RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}"
+        COMPONENT sourcemeta_hydra
+      LIBRARY DESTINATION "${CMAKE_INSTALL_LIBDIR}"
+        COMPONENT sourcemeta_hydra
+        NAMELINK_COMPONENT sourcemeta_hydra_dev
+      ARCHIVE DESTINATION "${CMAKE_INSTALL_LIBDIR}"
+        COMPONENT sourcemeta_hydra_dev)
+    install(EXPORT bearssl
+      DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/bearssl"
       COMPONENT sourcemeta_hydra_dev)
-  install(EXPORT bearssl
-    DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/bearssl"
-    COMPONENT sourcemeta_hydra_dev)
 
-  file(WRITE ${CMAKE_CURRENT_BINARY_DIR}/bearssl-config.cmake
-    "include(\"\${CMAKE_CURRENT_LIST_DIR}/bearssl.cmake\")\n"
-    "check_required_components(\"bearssl\")\n")
-  install(FILES
-    "${CMAKE_CURRENT_BINARY_DIR}/bearssl-config.cmake"
-    DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/bearssl"
-    COMPONENT sourcemeta_hydra_dev)
+    file(WRITE ${CMAKE_CURRENT_BINARY_DIR}/bearssl-config.cmake
+      "include(\"\${CMAKE_CURRENT_LIST_DIR}/bearssl.cmake\")\n"
+      "check_required_components(\"bearssl\")\n")
+    install(FILES
+      "${CMAKE_CURRENT_BINARY_DIR}/bearssl-config.cmake"
+      DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/bearssl"
+      COMPONENT sourcemeta_hydra_dev)
+  endif()
 
   set(BearSSL_FOUND ON)
 endif()
diff --git a/vendor/hydra/cmake/FindCURL.cmake b/vendor/hydra/cmake/FindCURL.cmake
index d3ba2906..34f83ef5 100644
--- a/vendor/hydra/cmake/FindCURL.cmake
+++ b/vendor/hydra/cmake/FindCURL.cmake
@@ -443,34 +443,36 @@ if(NOT CURL_FOUND)
       C_VISIBILITY_INLINES_HIDDEN FALSE
       EXPORT_NAME curl)
 
-  include(GNUInstallDirs)
-  install(TARGETS curl
-    EXPORT curl
-    PUBLIC_HEADER DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/curl"
-      COMPONENT sourcemeta_hydra_dev
-    PRIVATE_HEADER DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/curl"
-      COMPONENT sourcemeta_hydra_dev
-    RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}"
-      COMPONENT sourcemeta_hydra
-    LIBRARY DESTINATION "${CMAKE_INSTALL_LIBDIR}"
-      COMPONENT sourcemeta_hydra
-      NAMELINK_COMPONENT sourcemeta_hydra_dev
-    ARCHIVE DESTINATION "${CMAKE_INSTALL_LIBDIR}"
+  if(HYDRA_INSTALL)
+    include(GNUInstallDirs)
+    install(TARGETS curl
+      EXPORT curl
+      PUBLIC_HEADER DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/curl"
+        COMPONENT sourcemeta_hydra_dev
+      PRIVATE_HEADER DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/curl"
+        COMPONENT sourcemeta_hydra_dev
+      RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}"
+        COMPONENT sourcemeta_hydra
+      LIBRARY DESTINATION "${CMAKE_INSTALL_LIBDIR}"
+        COMPONENT sourcemeta_hydra
+        NAMELINK_COMPONENT sourcemeta_hydra_dev
+      ARCHIVE DESTINATION "${CMAKE_INSTALL_LIBDIR}"
+        COMPONENT sourcemeta_hydra_dev)
+    install(EXPORT curl
+      DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/curl"
       COMPONENT sourcemeta_hydra_dev)
-  install(EXPORT curl
-    DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/curl"
-    COMPONENT sourcemeta_hydra_dev)
 
-  # TODO: Why does `find_dependency(ZLIB)` fail to locate ZLIB
-  # if even `CMAKE_PREFIX_PATH` is correct?
-  file(WRITE ${CMAKE_CURRENT_BINARY_DIR}/curl-config.cmake
-    "include(\"\${CMAKE_CURRENT_LIST_DIR}/../zlib/zlib-config.cmake\")\n"
-    "include(\"\${CMAKE_CURRENT_LIST_DIR}/curl.cmake\")\n"
-    "check_required_components(\"curl\")\n")
-  install(FILES
-    "${CMAKE_CURRENT_BINARY_DIR}/curl-config.cmake"
-    DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/curl"
-    COMPONENT sourcemeta_hydra_dev)
+    # TODO: Why does `find_dependency(ZLIB)` fail to locate ZLIB
+    # if even `CMAKE_PREFIX_PATH` is correct?
+    file(WRITE ${CMAKE_CURRENT_BINARY_DIR}/curl-config.cmake
+      "include(\"\${CMAKE_CURRENT_LIST_DIR}/../zlib/zlib-config.cmake\")\n"
+      "include(\"\${CMAKE_CURRENT_LIST_DIR}/curl.cmake\")\n"
+      "check_required_components(\"curl\")\n")
+    install(FILES
+      "${CMAKE_CURRENT_BINARY_DIR}/curl-config.cmake"
+      DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/curl"
+      COMPONENT sourcemeta_hydra_dev)
+  endif()
 
   set(CURL_FOUND ON)
 endif()
diff --git a/vendor/hydra/cmake/FindZLIB.cmake b/vendor/hydra/cmake/FindZLIB.cmake
index d63b93e1..005bec11 100644
--- a/vendor/hydra/cmake/FindZLIB.cmake
+++ b/vendor/hydra/cmake/FindZLIB.cmake
@@ -53,31 +53,33 @@ if(NOT ZLIB_FOUND)
       WINDOWS_EXPORT_ALL_SYMBOLS TRUE
       EXPORT_NAME zlib)
 
-  include(GNUInstallDirs)
-  install(TARGETS zlib
-    EXPORT zlib
-    PUBLIC_HEADER DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
-      COMPONENT sourcemeta_hydra_dev
-    PRIVATE_HEADER DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
-      COMPONENT sourcemeta_hydra_dev
-    RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}"
-      COMPONENT sourcemeta_hydra
-    LIBRARY DESTINATION "${CMAKE_INSTALL_LIBDIR}"
-      COMPONENT sourcemeta_hydra
-      NAMELINK_COMPONENT sourcemeta_hydra_dev
-    ARCHIVE DESTINATION "${CMAKE_INSTALL_LIBDIR}"
+  if(HYDRA_INSTALL)
+    include(GNUInstallDirs)
+    install(TARGETS zlib
+      EXPORT zlib
+      PUBLIC_HEADER DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
+        COMPONENT sourcemeta_hydra_dev
+      PRIVATE_HEADER DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
+        COMPONENT sourcemeta_hydra_dev
+      RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}"
+        COMPONENT sourcemeta_hydra
+      LIBRARY DESTINATION "${CMAKE_INSTALL_LIBDIR}"
+        COMPONENT sourcemeta_hydra
+        NAMELINK_COMPONENT sourcemeta_hydra_dev
+      ARCHIVE DESTINATION "${CMAKE_INSTALL_LIBDIR}"
+        COMPONENT sourcemeta_hydra_dev)
+    install(EXPORT zlib
+      DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/zlib"
       COMPONENT sourcemeta_hydra_dev)
-  install(EXPORT zlib
-    DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/zlib"
-    COMPONENT sourcemeta_hydra_dev)
 
-  file(WRITE ${CMAKE_CURRENT_BINARY_DIR}/zlib-config.cmake
-    "include(\"\${CMAKE_CURRENT_LIST_DIR}/zlib.cmake\")\n"
-    "check_required_components(\"zlib\")\n")
-  install(FILES
-    "${CMAKE_CURRENT_BINARY_DIR}/zlib-config.cmake"
-    DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/zlib"
-    COMPONENT sourcemeta_hydra_dev)
+    file(WRITE ${CMAKE_CURRENT_BINARY_DIR}/zlib-config.cmake
+      "include(\"\${CMAKE_CURRENT_LIST_DIR}/zlib.cmake\")\n"
+      "check_required_components(\"zlib\")\n")
+    install(FILES
+      "${CMAKE_CURRENT_BINARY_DIR}/zlib-config.cmake"
+      DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/zlib"
+      COMPONENT sourcemeta_hydra_dev)
+  endif()
 
   set(ZLIB_FOUND ON)
 endif()
diff --git a/vendor/hydra/cmake/FinduSockets.cmake b/vendor/hydra/cmake/FinduSockets.cmake
index 160301c0..e00e6c22 100644
--- a/vendor/hydra/cmake/FinduSockets.cmake
+++ b/vendor/hydra/cmake/FinduSockets.cmake
@@ -54,31 +54,33 @@ if(NOT uSockets_FOUND)
       WINDOWS_EXPORT_ALL_SYMBOLS TRUE
       EXPORT_NAME usockets)
 
-  include(GNUInstallDirs)
-  install(TARGETS usockets
-    EXPORT usockets
-    PUBLIC_HEADER DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
-      COMPONENT sourcemeta_hydra_dev
-    PRIVATE_HEADER DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
-      COMPONENT sourcemeta_hydra_dev
-    RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}"
-      COMPONENT sourcemeta_hydra
-    LIBRARY DESTINATION "${CMAKE_INSTALL_LIBDIR}"
-      COMPONENT sourcemeta_hydra
-      NAMELINK_COMPONENT sourcemeta_hydra_dev
-    ARCHIVE DESTINATION "${CMAKE_INSTALL_LIBDIR}"
+  if(HYDRA_INSTALL)
+    include(GNUInstallDirs)
+    install(TARGETS usockets
+      EXPORT usockets
+      PUBLIC_HEADER DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
+        COMPONENT sourcemeta_hydra_dev
+      PRIVATE_HEADER DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
+        COMPONENT sourcemeta_hydra_dev
+      RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}"
+        COMPONENT sourcemeta_hydra
+      LIBRARY DESTINATION "${CMAKE_INSTALL_LIBDIR}"
+        COMPONENT sourcemeta_hydra
+        NAMELINK_COMPONENT sourcemeta_hydra_dev
+      ARCHIVE DESTINATION "${CMAKE_INSTALL_LIBDIR}"
+        COMPONENT sourcemeta_hydra_dev)
+    install(EXPORT usockets
+      DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/usockets"
       COMPONENT sourcemeta_hydra_dev)
-  install(EXPORT usockets
-    DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/usockets"
-    COMPONENT sourcemeta_hydra_dev)
 
-  file(WRITE ${CMAKE_CURRENT_BINARY_DIR}/usockets-config.cmake
-    "include(\"\${CMAKE_CURRENT_LIST_DIR}/usockets.cmake\")\n"
-    "check_required_components(\"usockets\")\n")
-  install(FILES
-    "${CMAKE_CURRENT_BINARY_DIR}/usockets-config.cmake"
-    DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/usockets"
-    COMPONENT sourcemeta_hydra_dev)
+    file(WRITE ${CMAKE_CURRENT_BINARY_DIR}/usockets-config.cmake
+      "include(\"\${CMAKE_CURRENT_LIST_DIR}/usockets.cmake\")\n"
+      "check_required_components(\"usockets\")\n")
+    install(FILES
+      "${CMAKE_CURRENT_BINARY_DIR}/usockets-config.cmake"
+      DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/usockets"
+      COMPONENT sourcemeta_hydra_dev)
+  endif()
 
   set(uSockets_FOUND ON)
 endif()
diff --git a/vendor/hydra/cmake/FinduWebSockets.cmake b/vendor/hydra/cmake/FinduWebSockets.cmake
index a28695a2..39587d52 100644
--- a/vendor/hydra/cmake/FinduWebSockets.cmake
+++ b/vendor/hydra/cmake/FinduWebSockets.cmake
@@ -62,31 +62,33 @@ if(NOT uWebSockets_FOUND)
       PRIVATE_HEADER "${UWEBSOCKETS_PRIVATE_HEADERS}"
       EXPORT_NAME uwebsockets)
 
-  include(GNUInstallDirs)
-  install(TARGETS uwebsockets
-    EXPORT uwebsockets
-    PUBLIC_HEADER DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/uwebsockets/src"
-      COMPONENT sourcemeta_hydra_dev
-    PRIVATE_HEADER DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/uwebsockets/src"
-      COMPONENT sourcemeta_hydra_dev
-    RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}"
-      COMPONENT sourcemeta_hydra
-    LIBRARY DESTINATION "${CMAKE_INSTALL_LIBDIR}"
-      COMPONENT sourcemeta_hydra
-      NAMELINK_COMPONENT sourcemeta_hydra_dev
-    ARCHIVE DESTINATION "${CMAKE_INSTALL_LIBDIR}"
+  if(HYDRA_INSTALL)
+    include(GNUInstallDirs)
+    install(TARGETS uwebsockets
+      EXPORT uwebsockets
+      PUBLIC_HEADER DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/uwebsockets/src"
+        COMPONENT sourcemeta_hydra_dev
+      PRIVATE_HEADER DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/uwebsockets/src"
+        COMPONENT sourcemeta_hydra_dev
+      RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}"
+        COMPONENT sourcemeta_hydra
+      LIBRARY DESTINATION "${CMAKE_INSTALL_LIBDIR}"
+        COMPONENT sourcemeta_hydra
+        NAMELINK_COMPONENT sourcemeta_hydra_dev
+      ARCHIVE DESTINATION "${CMAKE_INSTALL_LIBDIR}"
+        COMPONENT sourcemeta_hydra_dev)
+    install(EXPORT uwebsockets
+      DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/uwebsockets"
       COMPONENT sourcemeta_hydra_dev)
-  install(EXPORT uwebsockets
-    DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/uwebsockets"
-    COMPONENT sourcemeta_hydra_dev)
 
-  file(WRITE ${CMAKE_CURRENT_BINARY_DIR}/uwebsockets-config.cmake
-    "include(\"\${CMAKE_CURRENT_LIST_DIR}/uwebsockets.cmake\")\n"
-    "check_required_components(\"uwebsockets\")\n")
-  install(FILES
-    "${CMAKE_CURRENT_BINARY_DIR}/uwebsockets-config.cmake"
-    DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/uwebsockets"
-    COMPONENT sourcemeta_hydra_dev)
+    file(WRITE ${CMAKE_CURRENT_BINARY_DIR}/uwebsockets-config.cmake
+      "include(\"\${CMAKE_CURRENT_LIST_DIR}/uwebsockets.cmake\")\n"
+      "check_required_components(\"uwebsockets\")\n")
+    install(FILES
+      "${CMAKE_CURRENT_BINARY_DIR}/uwebsockets-config.cmake"
+      DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/uwebsockets"
+      COMPONENT sourcemeta_hydra_dev)
+  endif()
 
   set(uWebSockets_FOUND ON)
 endif()