diff --git a/src/writer/hlsl/generator_impl.cc b/src/writer/hlsl/generator_impl.cc
index 2b66d3fd84..dc91175193 100644
--- a/src/writer/hlsl/generator_impl.cc
+++ b/src/writer/hlsl/generator_impl.cc
@@ -1977,7 +1977,7 @@ bool GeneratorImpl::EmitStatement(std::ostream& out, ast::Statement* stmt) {
   if (auto* d = stmt->As<ast::DiscardStatement>()) {
     return EmitDiscard(out, d);
   }
-  if (auto* f = stmt->As<ast::FallthroughStatement>()) {
+  if (stmt->As<ast::FallthroughStatement>()) {
     make_indent(out);
     out << "/* fallthrough */" << std::endl;
     return true;
diff --git a/src/writer/msl/generator_impl.cc b/src/writer/msl/generator_impl.cc
index 1161be78d0..6fa0c6a06e 100644
--- a/src/writer/msl/generator_impl.cc
+++ b/src/writer/msl/generator_impl.cc
@@ -1736,7 +1736,7 @@ bool GeneratorImpl::EmitStatement(ast::Statement* stmt) {
   if (auto* d = stmt->As<ast::DiscardStatement>()) {
     return EmitDiscard(d);
   }
-  if (auto* f = stmt->As<ast::FallthroughStatement>()) {
+  if (stmt->As<ast::FallthroughStatement>()) {
     make_indent();
     out_ << "/* fallthrough */" << std::endl;
     return true;