diff --git a/distros/jazzy/overrides.nix b/distros/jazzy/overrides.nix
index daddee09d3..ccc384acac 100644
--- a/distros/jazzy/overrides.nix
+++ b/distros/jazzy/overrides.nix
@@ -42,36 +42,20 @@ in {
     fetchgitArgs.hash = "sha256-gztnxui9Fe/FTieMjdvfJjWHjkImtlsHn6fM1FruyME=";
   };
 
-  gz-cmake-vendor = lib.patchGzAmentVendorGit rosSuper.gz-cmake-vendor {
-    version = "3.5.4";
-    hash = "sha256-mP0bBPWWAoUFsUwKn95Eqv1lW3lJdPEu3hhfmiK3mNQ=";
-  };
+  gz-cmake-vendor = lib.patchGzAmentVendorGit rosSuper.gz-cmake-vendor { };
 
-  gz-common-vendor = (lib.patchGzAmentVendorGit rosSuper.gz-common-vendor {
-    version = "5.7.1";
-    hash = "sha256-vNCjCSQYCSUHXKwXnq8vwWXiSK2+cD3yPSLT1FdAWrE=";
-  }).overrideAttrs ({
+  gz-common-vendor = (lib.patchGzAmentVendorGit rosSuper.gz-common-vendor { }).overrideAttrs ({
     nativeBuildInputs ? [], ...
   }: {
     # https://github.com/gazebo-release/gz_common_vendor/pull/2
     nativeBuildInputs = nativeBuildInputs ++ [ self.pkg-config ];
   });
 
-  gz-dartsim-vendor = lib.patchAmentVendorGit rosSuper.gz-dartsim-vendor {
-    url = "https://github.com/dartsim/dart.git";
-    rev = "v6.13.2";
-    fetchgitArgs.hash = "sha256-AfKPqUiW6BsM98TIzTY2ZcFP1WvURs8/dGOzanIiB9g=";
-  };
+  gz-dartsim-vendor = lib.patchAmentVendorGit rosSuper.gz-dartsim-vendor { };
 
-  gz-fuel-tools-vendor = lib.patchGzAmentVendorGit rosSuper.gz-fuel-tools-vendor {
-    version = "9.1.1";
-    hash = "sha256-XQoBcCtzwzzPypS1kIeTCIbjtxrzaW3JvZLCYbwXAOk=";
-  };
+  gz-fuel-tools-vendor = lib.patchGzAmentVendorGit rosSuper.gz-fuel-tools-vendor { };
 
-  gz-gui-vendor = (lib.patchGzAmentVendorGit rosSuper.gz-gui-vendor {
-    version = "8.4.0";
-    hash = "sha256-gf9XZzAX2g6r9ThIA0v2H2X/+uu9VnwvyvrdL5ZazM0=";
-  }).overrideAttrs ({
+  gz-gui-vendor = (lib.patchGzAmentVendorGit rosSuper.gz-gui-vendor { }).overrideAttrs ({
     postInstall ? "", ...
   }: {
     # "RPATH of binary libGrid3D.so contains a forbidden reference to
@@ -81,58 +65,27 @@ in {
     '';
   });
 
-  gz-launch-vendor = lib.patchGzAmentVendorGit rosSuper.gz-launch-vendor {
-    version = "7.1.1";
-    hash = "sha256-S63DWe/c3cnEztxr3uJc0A4AmuiQk4o6m9yXj0X97Yk=";
-  };
+  gz-launch-vendor = lib.patchGzAmentVendorGit rosSuper.gz-launch-vendor { };
 
-  gz-math-vendor = lib.patchGzAmentVendorGit rosSuper.gz-math-vendor {
-    version = "7.5.2";
-    hash = "sha256-LwYeyv8nwX06n5ju+ra2uqNMedMSLRumem8qDHXtNns=";
-  };
+  gz-math-vendor = lib.patchGzAmentVendorGit rosSuper.gz-math-vendor { };
 
-  gz-msgs-vendor = lib.patchGzAmentVendorGit rosSuper.gz-msgs-vendor {
-    version = "10.3.2";
-    hash = "sha256-gxhRqLzBCaDmK67T5RryDpxbDR3WLgV9DFs7w6ieMxQ=";
-  };
+  gz-msgs-vendor = lib.patchGzAmentVendorGit rosSuper.gz-msgs-vendor { };
 
-  gz-ogre-next-vendor = (lib.patchAmentVendorGit rosSuper.gz-ogre-next-vendor {
-    url = "https://github.com/OGRECave/ogre-next.git";
-    rev = "v2.3.3";
-    fetchgitArgs.hash = "sha256-elSj35LwsLzj1ssDPsk9NW/KSXfiOGYmw9hQSAWdpFM=";
-  }).overrideAttrs({ ... }: {
+  gz-ogre-next-vendor = (lib.patchAmentVendorGit rosSuper.gz-ogre-next-vendor { }).overrideAttrs({ ... }: {
     dontFixCmake = true;
   });
 
-  gz-physics-vendor = lib.patchGzAmentVendorGit rosSuper.gz-physics-vendor {
-    version = "7.5.0";
-    hash = "sha256-75myTqDeEybvj5rsJxRambLPle1cen6HIatZGbVoXro=";
-  };
+  gz-physics-vendor = lib.patchGzAmentVendorGit rosSuper.gz-physics-vendor { };
 
-  gz-plugin-vendor = lib.patchGzAmentVendorGit rosSuper.gz-plugin-vendor {
-    version = "2.0.4";
-    hash = "sha256-iL4+EdFFAU55FVqE/CvyTv1zNaXxBWqWx44L0BeG2MU=";
-  };
+  gz-plugin-vendor = lib.patchGzAmentVendorGit rosSuper.gz-plugin-vendor { };
 
-  gz-rendering-vendor = lib.patchGzAmentVendorGit rosSuper.gz-rendering-vendor {
-    version = "8.2.2";
-    hash = "sha256-x+QHn8d+19U12CG1+HEmP0KcM3beY00Vvrc8mrxvAs0=";
-  };
+  gz-rendering-vendor = lib.patchGzAmentVendorGit rosSuper.gz-rendering-vendor { };
 
-  gz-sensors-vendor = lib.patchGzAmentVendorGit rosSuper.gz-sensors-vendor {
-    version = "8.2.2";
-    hash = "sha256-TRDMCMesJXVSVGA3bnRngtXTi4VVf0y12AJQ79EEMiI=";
-  };
+  gz-sensors-vendor = lib.patchGzAmentVendorGit rosSuper.gz-sensors-vendor { };
 
-  gz-sim-vendor = lib.patchGzAmentVendorGit rosSuper.gz-sim-vendor {
-    version = "8.9.0";
-    hash = "sha256-hvhq2XBzcIoupJdJyJzk38LDXoEnd9iBCCiXvPZsPqY=";
-  };
+  gz-sim-vendor = lib.patchGzAmentVendorGit rosSuper.gz-sim-vendor { };
 
-  gz-tools-vendor = (lib.patchGzAmentVendorGit rosSuper.gz-tools-vendor {
-    version = "2.0.2";
-    hash = "sha256-CY+W1jWIkszKwKuLgKmJpZMXHn0RnueMHFSDhOXIzLg=";
-  }).overrideAttrs({
+  gz-tools-vendor = (lib.patchGzAmentVendorGit rosSuper.gz-tools-vendor { }).overrideAttrs({
     nativeBuildInputs ? [],
     propagatedNativeBuildInputs ? [],
     qtWrapperArgs ? [],
@@ -154,19 +107,13 @@ in {
     '';
   });
 
-  gz-transport-vendor = (lib.patchGzAmentVendorGit rosSuper.gz-transport-vendor {
-    version = "13.4.1";
-    hash = "sha256-hCP+yVoyl1c3KNmQ5jKrYvPT1IlAy9JkCh0c0mOF+KM=";
-  }).overrideAttrs({
+  gz-transport-vendor = (lib.patchGzAmentVendorGit rosSuper.gz-transport-vendor { }).overrideAttrs({
     buildInputs ? [], ...
   }: {
     buildInputs = buildInputs ++ [ self.libsodium ];
   });
 
-  gz-utils-vendor = lib.patchGzAmentVendorGit rosSuper.gz-utils-vendor {
-    version = "2.2.1";
-    hash = "sha256-utVW8pTP/emEWblTxVb6jzulKdxss+2VfS552MWMqm4=";
-  };
+  gz-utils-vendor = lib.patchGzAmentVendorGit rosSuper.gz-utils-vendor { };
 
   iceoryx-hoofs = rosSuper.iceoryx-hoofs.overrideAttrs ({
     patches ? [], ...
@@ -222,9 +169,6 @@ in {
   });
 
   rviz-ogre-vendor = lib.patchAmentVendorGit rosSuper.rviz-ogre-vendor {
-    url = "https://github.com/OGRECave/ogre.git";
-    rev = "v1.12.10";
-    fetchgitArgs.hash = "sha256-Z0ixdSmkV93coBBVZ5R3lPLfVMXRfWsFz/RsSyqPWFY=";
     tarSourceArgs.hook = let
       version = "1.79";
       imgui = self.fetchFromGitHub rec {
@@ -255,10 +199,7 @@ in {
     sha256 = "sha256-TyFt3d78GidhDGD17KgjAaZl/qvAcGJP8lmu4EOxpYg=";
   };
 
-  sdformat-vendor = lib.patchGzAmentVendorGit rosSuper.sdformat-vendor {
-    version = "14.7.0";
-    hash = "sha256-p2e01bCoMpDhia1yOFa5wIP2ritBiWNT5jYbp/bg1+g=";
-  };
+  sdformat-vendor = lib.patchGzAmentVendorGit rosSuper.sdformat-vendor { };
 
   urdfdom = rosSuper.urdfdom.overrideAttrs ({
     patches ? [], ...
diff --git a/distros/rolling/overrides.nix b/distros/rolling/overrides.nix
index db0231aa33..d6dcedea7a 100644
--- a/distros/rolling/overrides.nix
+++ b/distros/rolling/overrides.nix
@@ -42,36 +42,20 @@ in {
     fetchgitArgs.hash = "sha256-gztnxui9Fe/FTieMjdvfJjWHjkImtlsHn6fM1FruyME=";
   };
 
-  gz-cmake-vendor = lib.patchGzAmentVendorGit rosSuper.gz-cmake-vendor {
-    version = "4.1.1";
-    hash = "sha256-BWgRm+3UW65Cu7TqXtFFG05JlYF52dbpAsIE8aDnJM0=";
-  };
+  gz-cmake-vendor = lib.patchGzAmentVendorGit rosSuper.gz-cmake-vendor { };
 
-  gz-common-vendor = (lib.patchGzAmentVendorGit rosSuper.gz-common-vendor {
-    version = "6.0.0";
-    hash = "sha256-Oo4dGN2vsVaElKf/KYjjJq6tlYLRPr0/uh6urGxvDdc=";
-  }).overrideAttrs ({
+  gz-common-vendor = (lib.patchGzAmentVendorGit rosSuper.gz-common-vendor { }).overrideAttrs ({
     nativeBuildInputs ? [], ...
   }: {
     # https://github.com/gazebo-release/gz_common_vendor/pull/2
     nativeBuildInputs = nativeBuildInputs ++ [ self.pkg-config ];
   });
 
-  gz-dartsim-vendor = lib.patchAmentVendorGit rosSuper.gz-dartsim-vendor {
-    url = "https://github.com/dartsim/dart.git";
-    rev = "v6.13.2";
-    fetchgitArgs.hash = "sha256-AfKPqUiW6BsM98TIzTY2ZcFP1WvURs8/dGOzanIiB9g=";
-  };
+  gz-dartsim-vendor = lib.patchAmentVendorGit rosSuper.gz-dartsim-vendor { };
 
-  gz-fuel-tools-vendor = lib.patchGzAmentVendorGit rosSuper.gz-fuel-tools-vendor {
-    version = "10.0.0";
-    hash = "sha256-9WskZnci7D09aW32lzmdtlhRBM+hcmhG6iNgf3OC1js=";
-  };
+  gz-fuel-tools-vendor = lib.patchGzAmentVendorGit rosSuper.gz-fuel-tools-vendor { };
 
-  gz-gui-vendor = (lib.patchGzAmentVendorGit rosSuper.gz-gui-vendor {
-    version = "9.0.0";
-    hash = "sha256-/YJW6XmdGwbyd5Nx3wcTqnRlpwE1unVGaNX91qfZmiM=";
-  }).overrideAttrs ({
+  gz-gui-vendor = (lib.patchGzAmentVendorGit rosSuper.gz-gui-vendor { }).overrideAttrs ({
     postInstall ? "", ...
   }: {
     # "RPATH of binary libGrid3D.so contains a forbidden reference to
@@ -81,58 +65,27 @@ in {
     '';
   });
 
-  gz-launch-vendor = lib.patchGzAmentVendorGit rosSuper.gz-launch-vendor {
-    version = "8.0.0";
-    hash = "sha256-K2W2SSlhJvF9mxEMNa7tZa3/3/LIvxZMGeVb0Mi6Vso=";
-  };
+  gz-launch-vendor = lib.patchGzAmentVendorGit rosSuper.gz-launch-vendor { };
 
-  gz-math-vendor = lib.patchGzAmentVendorGit rosSuper.gz-math-vendor {
-    version = "8.1.0";
-    hash = "sha256-3jQk98HJ0ru2Q4fTqoiaPRaIHaWQKQlnqj+gN2PLxkE=";
-  };
+  gz-math-vendor = lib.patchGzAmentVendorGit rosSuper.gz-math-vendor { };
 
-  gz-msgs-vendor = lib.patchGzAmentVendorGit rosSuper.gz-msgs-vendor {
-    version = "11.0.2";
-    hash = "sha256-PUhFOmVPRiOVWfOjAU8z8dcxKPdcoTrgRwDGXP/vsUs=";
-  };
+  gz-msgs-vendor = lib.patchGzAmentVendorGit rosSuper.gz-msgs-vendor { };
 
-  gz-ogre-next-vendor = (lib.patchAmentVendorGit rosSuper.gz-ogre-next-vendor {
-    url = "https://github.com/OGRECave/ogre-next.git";
-    rev = "v2.3.3";
-    fetchgitArgs.hash = "sha256-elSj35LwsLzj1ssDPsk9NW/KSXfiOGYmw9hQSAWdpFM=";
-  }).overrideAttrs({ ... }: {
+  gz-ogre-next-vendor = (lib.patchAmentVendorGit rosSuper.gz-ogre-next-vendor { }).overrideAttrs({ ... }: {
     dontFixCmake = true;
   });
 
-  gz-physics-vendor = lib.patchGzAmentVendorGit rosSuper.gz-physics-vendor {
-    version = "8.0.0";
-    hash = "sha256-PjwrJG3xvRYrkHDTaBUgoaW8NglEYDPuJrk4QjJjTHU=";
-  };
+  gz-physics-vendor = lib.patchGzAmentVendorGit rosSuper.gz-physics-vendor { };
 
-  gz-plugin-vendor = lib.patchGzAmentVendorGit rosSuper.gz-plugin-vendor {
-    version = "3.0.0";
-    hash = "sha256-h2Dx0KcFmJlS67q0v1zbd9nQkTCKgHkxt5KKTT5v+fw=";
-  };
+  gz-plugin-vendor = lib.patchGzAmentVendorGit rosSuper.gz-plugin-vendor { };
 
-  gz-rendering-vendor = lib.patchGzAmentVendorGit rosSuper.gz-rendering-vendor {
-    version = "9.0.0";
-    hash = "sha256-e3OPLeqV6OgjnQrbpwRj59e7Z0BqN2wOee/gAaMHfqU=";
-  };
+  gz-rendering-vendor = lib.patchGzAmentVendorGit rosSuper.gz-rendering-vendor { };
 
-  gz-sensors-vendor = lib.patchGzAmentVendorGit rosSuper.gz-sensors-vendor {
-    version = "9.0.0";
-    hash = "sha256-8Ato7/YRL7JebbVPASD6VF9lf/Uyq26MIg2l+jQ4GDk=";
-  };
+  gz-sensors-vendor = lib.patchGzAmentVendorGit rosSuper.gz-sensors-vendor { };
 
-  gz-sim-vendor = lib.patchGzAmentVendorGit rosSuper.gz-sim-vendor {
-    version = "9.0.0";
-    hash = "sha256-gsWKknqcTiJc4YHIkmg1YGItwHG1As2OUnpPBQIwqj8=";
-  };
+  gz-sim-vendor = lib.patchGzAmentVendorGit rosSuper.gz-sim-vendor { };
 
-  gz-tools-vendor = (lib.patchGzAmentVendorGit rosSuper.gz-tools-vendor {
-    version = "2.0.2";
-    hash = "sha256-CY+W1jWIkszKwKuLgKmJpZMXHn0RnueMHFSDhOXIzLg=";
-  }).overrideAttrs({
+  gz-tools-vendor = (lib.patchGzAmentVendorGit rosSuper.gz-tools-vendor { }).overrideAttrs({
     nativeBuildInputs ? [],
     propagatedNativeBuildInputs ? [],
     qtWrapperArgs ? [],
@@ -154,19 +107,13 @@ in {
     '';
   });
 
-  gz-transport-vendor = (lib.patchGzAmentVendorGit rosSuper.gz-transport-vendor {
-    version = "14.0.0";
-    hash = "sha256-zoGphy2cpmqJsnyS1LNVm4eGtHCWkAwIblga4RdVj4k=";
-  }).overrideAttrs({
+  gz-transport-vendor = (lib.patchGzAmentVendorGit rosSuper.gz-transport-vendor { }).overrideAttrs({
     buildInputs ? [], ...
   }: {
     buildInputs = buildInputs ++ [ self.libsodium ];
   });
 
-  gz-utils-vendor = lib.patchGzAmentVendorGit rosSuper.gz-utils-vendor {
-    version = "3.1.0";
-    hash = "sha256-pbbFO/4h3Tos+uigPC8XHWzv+Yuyd6EdzLWQPdmXaN8=";
-  };
+  gz-utils-vendor = lib.patchGzAmentVendorGit rosSuper.gz-utils-vendor { };
 
   iceoryx-hoofs = rosSuper.iceoryx-hoofs.overrideAttrs ({
     patches ? [], ...
@@ -229,9 +176,6 @@ in {
   };
 
   rviz-ogre-vendor = lib.patchAmentVendorGit rosSuper.rviz-ogre-vendor {
-    url = "https://github.com/OGRECave/ogre.git";
-    rev = "v1.12.10";
-    fetchgitArgs.hash = "sha256-Z0ixdSmkV93coBBVZ5R3lPLfVMXRfWsFz/RsSyqPWFY=";
     tarSourceArgs.hook = let
       version = "1.79";
       imgui = self.fetchFromGitHub rec {
@@ -257,10 +201,7 @@ in {
     '';
   });
 
-  sdformat-vendor = lib.patchGzAmentVendorGit rosSuper.sdformat-vendor {
-    version = "15.1.1";
-    hash = "sha256-4/0pVaev++v0+wHQiGeTl8XtTDzh2li32dND0EjfjwA=";
-  };
+  sdformat-vendor = lib.patchGzAmentVendorGit rosSuper.sdformat-vendor { };
 
   shared-queues-vendor = lib.patchVendorUrl rosSuper.shared-queues-vendor {
     url = "https://github.com/cameron314/readerwriterqueue/archive/ef7dfbf553288064347d51b8ac335f1ca489032a.zip";
diff --git a/lib/ament_cmake_vendor_packageConfig.cmake b/lib/ament_cmake_vendor_packageConfig.cmake
new file mode 100644
index 0000000000..cb835d4e71
--- /dev/null
+++ b/lib/ament_cmake_vendor_packageConfig.cmake
@@ -0,0 +1,32 @@
+# CMake package that defines alternative version of ament_vendor macro
+# to extract information about vendored source to
+# vendored-source.json. Normally, the ament_vendor macro is defined in
+# the ament_cmake_vendor_package and it downloads the vendored source
+# code at compile time. This is not possible with Nix, because Nix
+# builds packages without network access. Therefore, we inject this
+# alternative macro to cmake at update time and it extracts the
+# information needed by Nix to download the source code. The main
+# entry point to all this functionality is in the patchAmentVendorGit
+# function.
+
+if(NOT ament_cmake_vendor_package_FIND_QUIETLY)
+  message(STATUS "Found ament_cmake_vendor_package: Dummy version for Nix patching (${ament_cmake_vendor_package_DIR})")
+endif()
+
+find_program(JQ jq)
+find_program(NIX_PREFETCH_GIT nix-prefetch-git)
+
+macro(ament_vendor TARGET_NAME)
+  cmake_parse_arguments(_ARG "GLOBAL_HOOK;SKIP_INSTALL" "SOURCE_SUBDIR;VCS_TYPE;VCS_URL;VCS_VERSION;SATISFIED" "CMAKE_ARGS;PATCHES" ${ARGN})
+  if(_ARG_UNPARSED_ARGUMENTS)
+    message(FATAL_ERROR "ament_vendor() called with unused arguments: "
+      "${_ARG_UNPARSED_ARGUMENTS}")
+  endif()
+
+  execute_process(
+    COMMAND ${NIX_PREFETCH_GIT} --url ${_ARG_VCS_URL} --rev ${_ARG_VCS_VERSION}
+    COMMAND ${JQ} "{url: \"${_ARG_VCS_URL}\", rev: \"${_ARG_VCS_VERSION}\", hash: .hash}"
+    OUTPUT_FILE ${CMAKE_BINARY_DIR}/vendored-source.json
+    COMMAND_ECHO STDOUT
+    COMMAND_ERROR_IS_FATAL ANY)
+endmacro()
diff --git a/lib/default.nix b/lib/default.nix
index 7ea84179c5..66b1debd86 100644
--- a/lib/default.nix
+++ b/lib/default.nix
@@ -81,51 +81,80 @@
   # Patch a vendored download that uses ament_vendor() with a Git repo as the
   # source.
   patchAmentVendorGit = pkg: {
-    url,
-    originalUrl ? url,
-    rev, # Must correspond to the VCS_VERSION argument
     file ? "CMakeLists.txt",
     fetchgitArgs ? {},
     tarSourceArgs ? {}
   }: pkg.overrideAttrs ({
     nativeBuildInputs ? [],
+    passthru ? {},
     postPatch ? "", ...
   }: let
+    vendoredSourceJson = "${dirOf pkg.meta.position}/vendored-source.json";
+    inherit (builtins) stringLength substring pathExists;
+    nameStart = 5 + stringLength pkg.rosDistro; # e.g. ros-jazzy- => 10
+    attr = substring nameStart (-1) pkg.pname;
+    errMsg = ''
+      error: File ${vendoredSourceJson} missing.
+      Run "$(nix-build -A rosPackages.${pkg.rosDistro}.${attr}.updateAmentVendor)" to create it.
+    '';
+    sourceInfo = builtins.fromJSON (builtins.readFile vendoredSourceJson);
     # ament_vendor doesn't allow patches for path inputs, so we have to pack it
     # into a tar first. Additionally, vcstool only accepts tarballs with the
     # version number as the root directory name.
-    vendor = lib.tarSource tarSourceArgs (self.fetchgit (fetchgitArgs // {
-      name = rev;
-      inherit url rev;
-    }));
+    vendor = lib.tarSource tarSourceArgs (
+      self.fetchgit (sourceInfo // fetchgitArgs // {
+        name = sourceInfo.rev;
+      }));
   in {
     # CMake ExternalProject patches are applied with git apply
     nativeBuildInputs = nativeBuildInputs ++ [ self.git ];
-    postPatch = ''
-      sed -i '\|VCS_URL\s*${originalUrl}|c\
+    postPatch = (if pathExists vendoredSourceJson then ''
+      sed -i '\|VCS_URL\s*|c\
         VCS_URL "file://${vendor}"\
         VCS_TYPE tar' \
         ${lib.escapeShellArg file}
-    '' + postPatch;
+    '' else ''
+      echo >&2 ${lib.escapeShellArg errMsg}
+      exit 1
+    '') + postPatch;
+    passthru = passthru // {
+      # Script to automatically update vendored-source.json by running
+      # CMake with injected modified version of ament_cmake macro.
+      updateAmentVendor = let
+        source = self.srcOnly pkg;
+        sourceDrvPath = builtins.unsafeDiscardOutputDependency source.drvPath;
+        amentVendorNix = self.runCommand "ament_cmake_vendor_package_nix" {} ''
+          install -D ${./ament_cmake_vendor_packageConfig.cmake} $out/ament_cmake_vendor_packageConfig.cmake
+        '';
+        updateScript = self.writeShellScript "ament-vendor-update.sh" ''
+          set -eo pipefail
+          cd "$(${self.coreutils}/bin/mktemp -d)"
+          trap "${self.coreutils}/bin/rm -rf '$PWD'" SIGINT SIGTERM ERR EXIT
+          source "$stdenv/setup"
+          export NIX_SSL_CERT_FILE="${self.cacert}/etc/ssl/certs/ca-bundle.crt"
+          # Inject our version of ament_cmake_vendor_package
+          export PATH="${lib.makeBinPath (with self; [ nix-prefetch-git jq ])}:$PATH"
+          export CMAKE_PREFIX_PATH=${amentVendorNix}
+          phases="''${prePhases[*]:-} unpackPhase patchPhase ''${preConfigurePhases[*]:-} configurePhase ''${preBuildPhases[*]:-}" \
+            genericBuild
+          # Copy the resulting data to package source directory
+          cp -v vendored-source.json ${dirOf pkg.meta.position}
+        '';
+      in self.writeShellScript "update-${pkg.pname}" ''
+        set -eo pipefail
+        echo ============== Updating ${pkg.pname} ==============
+        NIX_BUILD_SHELL=${self.runtimeShell} nix-shell --pure ${sourceDrvPath} --run ${updateScript}
+      '';
+    };
   });
 
   # patchAmentVendorGit specialized for gz-*-vendor packages. In
-  # addition to patching ament_vendor() calls, it adds a check to
-  # CMakeLists.txt to detect upstream updates of the vendored package
-  # version.
+  # addition to patching ament_vendor() calls, it patches other things
+  # in CMakeLists.txt.
   patchGzAmentVendorGit = pkg: {
-    version,
-    hash,
     tarSourceArgs ? {}
   }: let
-    stem = lib.strings.removeSuffix "-vendor"
-      (lib.strings.removePrefix "ros-${pkg.rosDistro}-" pkg.pname); # e.g. gz-cmake
-    majorNum = lib.versions.major version;
     patchedPkg = lib.patchAmentVendorGit pkg {
-      url = "https://github.com/gazebosim/${stem}.git";
-      originalUrl = "https://github.com/gazebosim/\${GITHUB_NAME}.git";
-      rev = "${stem}${majorNum}_${version}"; # e.g. "gz-cmake3_3.5.3"
-      fetchgitArgs.hash = hash;
       inherit tarSourceArgs;
     };
   in patchedPkg.overrideAttrs ({
@@ -137,12 +166,6 @@
         --replace-fail 'opt/''${PROJECT_NAME}/extra_cmake' 'share/extra_cmake'
       substituteInPlace *-extras.cmake.in \
         --replace-fail 'opt/@PROJECT_NAME@/extra_cmake' 'share/extra_cmake'
-
-      cat >> CMakeLists.txt <<'EOF'
-      if(NOT ''${LIB_VER} VERSION_EQUAL "${version}")
-        message(FATAL_ERROR "Mismatch in ${pname} version (Nix: ${version}, upstream: ''${LIB_VER}). Fix this in overrides.nix.")
-      endif()
-      EOF
     '';
   });