diff --git a/gen/build/build.rs b/gen/build/build.rs
index b8ff9dda..c53bef7a 100644
--- a/gen/build/build.rs
+++ b/gen/build/build.rs
@@ -1,29 +1 @@
-use std::io::{self, Write};
-use std::path::Path;
-use std::process;
-
-const NOSYMLINK: &str = "
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-When building `cxx` from a git clone, git's symlink support needs
-to be enabled on platforms that have it off by default (Windows).
-Either use:
-
-   $ git config --global core.symlinks true
-
-prior to cloning, or else use:
-
-   $ git clone -c core.symlinks=true ...
-
-for the clone.
-
-Symlinks are only required for local development, not for building
-`cxx` as a (possibly transitive) dependency from crates.io.
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-";
-
-fn main() {
-    if !Path::new("src/syntax/mod.rs").exists() {
-        let _ = io::stderr().lock().write_all(NOSYMLINK.as_bytes());
-        process::exit(1);
-    }
-}
+include!("../../tools/cargo/build.rs");
diff --git a/gen/cmd/build.rs b/gen/cmd/build.rs
index b8ff9dda..c53bef7a 100644
--- a/gen/cmd/build.rs
+++ b/gen/cmd/build.rs
@@ -1,29 +1 @@
-use std::io::{self, Write};
-use std::path::Path;
-use std::process;
-
-const NOSYMLINK: &str = "
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-When building `cxx` from a git clone, git's symlink support needs
-to be enabled on platforms that have it off by default (Windows).
-Either use:
-
-   $ git config --global core.symlinks true
-
-prior to cloning, or else use:
-
-   $ git clone -c core.symlinks=true ...
-
-for the clone.
-
-Symlinks are only required for local development, not for building
-`cxx` as a (possibly transitive) dependency from crates.io.
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-";
-
-fn main() {
-    if !Path::new("src/syntax/mod.rs").exists() {
-        let _ = io::stderr().lock().write_all(NOSYMLINK.as_bytes());
-        process::exit(1);
-    }
-}
+include!("../../tools/cargo/build.rs");
diff --git a/gen/lib/build.rs b/gen/lib/build.rs
index b8ff9dda..c53bef7a 100644
--- a/gen/lib/build.rs
+++ b/gen/lib/build.rs
@@ -1,29 +1 @@
-use std::io::{self, Write};
-use std::path::Path;
-use std::process;
-
-const NOSYMLINK: &str = "
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-When building `cxx` from a git clone, git's symlink support needs
-to be enabled on platforms that have it off by default (Windows).
-Either use:
-
-   $ git config --global core.symlinks true
-
-prior to cloning, or else use:
-
-   $ git clone -c core.symlinks=true ...
-
-for the clone.
-
-Symlinks are only required for local development, not for building
-`cxx` as a (possibly transitive) dependency from crates.io.
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-";
-
-fn main() {
-    if !Path::new("src/syntax/mod.rs").exists() {
-        let _ = io::stderr().lock().write_all(NOSYMLINK.as_bytes());
-        process::exit(1);
-    }
-}
+include!("../../tools/cargo/build.rs");
diff --git a/macro/build.rs b/macro/build.rs
index b8ff9dda..927f72b2 100644
--- a/macro/build.rs
+++ b/macro/build.rs
@@ -1,29 +1 @@
-use std::io::{self, Write};
-use std::path::Path;
-use std::process;
-
-const NOSYMLINK: &str = "
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-When building `cxx` from a git clone, git's symlink support needs
-to be enabled on platforms that have it off by default (Windows).
-Either use:
-
-   $ git config --global core.symlinks true
-
-prior to cloning, or else use:
-
-   $ git clone -c core.symlinks=true ...
-
-for the clone.
-
-Symlinks are only required for local development, not for building
-`cxx` as a (possibly transitive) dependency from crates.io.
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-";
-
-fn main() {
-    if !Path::new("src/syntax/mod.rs").exists() {
-        let _ = io::stderr().lock().write_all(NOSYMLINK.as_bytes());
-        process::exit(1);
-    }
-}
+include!("../tools/cargo/build.rs");
diff --git a/tools/cargo/build.rs b/tools/cargo/build.rs
new file mode 100644
index 00000000..b8ff9dda
--- /dev/null
+++ b/tools/cargo/build.rs
@@ -0,0 +1,29 @@
+use std::io::{self, Write};
+use std::path::Path;
+use std::process;
+
+const NOSYMLINK: &str = "
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+When building `cxx` from a git clone, git's symlink support needs
+to be enabled on platforms that have it off by default (Windows).
+Either use:
+
+   $ git config --global core.symlinks true
+
+prior to cloning, or else use:
+
+   $ git clone -c core.symlinks=true ...
+
+for the clone.
+
+Symlinks are only required for local development, not for building
+`cxx` as a (possibly transitive) dependency from crates.io.
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+";
+
+fn main() {
+    if !Path::new("src/syntax/mod.rs").exists() {
+        let _ = io::stderr().lock().write_all(NOSYMLINK.as_bytes());
+        process::exit(1);
+    }
+}