diff --git a/build/build.rs b/build/build.rs
index 9a43a65..333e638 100644
--- a/build/build.rs
+++ b/build/build.rs
@@ -38,6 +38,11 @@ fn main() {
         }
         command.arg("--version");
 
+        // Allow wrapper scripts or alternate compilers to tell that this is
+        // `rustversion` running --version, so that they can stick to rustc's
+        // version format. https://github.com/dtolnay/rustversion/issues/67
+        command.env("RUSTVERSION", "1");
+
         let output = match command.output() {
             Ok(output) => output,
             Err(e) => {