diff --git a/unix/mksyscall.go b/unix/mksyscall.go
index f6678425..a8d73bb9 100644
--- a/unix/mksyscall.go
+++ b/unix/mksyscall.go
@@ -86,16 +86,14 @@ func parseParam(p string) Param {
 }
 
 func main() {
-	// Get the OS and architecture (using GOARCH_TARGET if it exists)
-	goos := os.Getenv("GOOS")
+	goos := os.Getenv("GOOS_TARGET")
+	if goos == "" {
+		goos = os.Getenv("GOOS")
+	}
 	if goos == "" {
 		fmt.Fprintln(os.Stderr, "GOOS not defined in environment")
 		os.Exit(1)
 	}
-	goarch := os.Getenv("GOARCH_TARGET")
-	if goarch == "" {
-		goarch = os.Getenv("GOARCH")
-	}
 
 	// Check that we are using the Docker-based build system if we should
 	if goos == "linux" {