diff --git a/services/backup/blob_client/build.rs b/services/backup/blob_client/build.rs
--- a/services/backup/blob_client/build.rs
+++ b/services/backup/blob_client/build.rs
@@ -1,7 +1,7 @@
 const PROTO_DIR: &'static str = "../../../shared/protos";
 
 fn main() -> Result<(), std::io::Error> {
-  let _build = cxx_build::bridge("src/lib.rs").flag_if_supported("-std=c++17");
+  let _build = cxx_build::bridge("src/lib.rs").flag("-std=c++17");
   println!("cargo:rerun-if-changed=src/lib.rs");
 
   tonic_build::compile_protos(format!("{}/blob.proto", PROTO_DIR))?;
diff --git a/services/tunnelbroker/rust-lib/build.rs b/services/tunnelbroker/rust-lib/build.rs
--- a/services/tunnelbroker/rust-lib/build.rs
+++ b/services/tunnelbroker/rust-lib/build.rs
@@ -1,4 +1,4 @@
 fn main() {
-  let _build = cxx_build::bridge("src/lib.rs").flag_if_supported("-std=c++17");
+  let _build = cxx_build::bridge("src/lib.rs").flag("-std=c++17");
   println!("cargo:rerun-if-changed=src/lib.rs");
 }