diff --git a/src/test.cpp b/src/test.cpp
index 280d4f0..f798693 100644
--- a/src/test.cpp
+++ b/src/test.cpp
@@ -270,9 +270,10 @@ TEST_CASE("bench3") {
   bench.batch(json.size());
   bench.unit("byte");
   auto *parser = WeaselJsonParser_create(1024, &c, nullptr, 0);
+  std::string copy;
   for (size_t stride = 128; stride <= json.size(); stride *= 2) {
     bench.run("parser3 (stride: " + std::to_string(stride) + ")", [&]() {
-      auto copy = json;
+      copy = json;
       WeaselJsonParser_reset(parser);
       for (size_t i = 0; i < copy.size(); i += stride) {
         if (WeaselJsonParser_parse(parser, copy.data() + i,
@@ -383,10 +384,11 @@ TEST_CASE("bench input types") {
       bench.doNotOptimizeAway(doc);
     });
 
+    std::string copy;
     {
       auto *parser = WeaselJsonParser_create(1024, &c, nullptr, 0);
       bench.run("parser3 " + name, [&]() {
-        auto copy = json;
+        copy = json;
         WeaselJsonParser_reset(parser);
         if (WeaselJsonParser_parse(parser, copy.data(), copy.size()) !=
             WeaselJson_AGAIN) {
@@ -401,7 +403,7 @@ TEST_CASE("bench input types") {
     {
       auto *parser = WeaselJsonParser_create(1024, &c, nullptr, WeaselJsonRaw);
       bench.run("parser3 (raw) " + name, [&]() {
-        auto copy = json;
+        copy = json;
         WeaselJsonParser_reset(parser);
         if (WeaselJsonParser_parse(parser, copy.data(), copy.size()) !=
             WeaselJson_AGAIN) {