diff --git a/tests/utils.h b/tests/utils.h
index acd8bc6..94ff050 100644
--- a/tests/utils.h
+++ b/tests/utils.h
@@ -290,3 +290,13 @@
 
   size_t start_count_ = CountOpenFds();
 };
+
+// From <benchmark/benchmark.h>.
+template <class Tp>
+static inline void DoNotOptimize(Tp const& value) {
+  asm volatile("" : : "r,m"(value) : "memory");
+}
+template <class Tp>
+static inline void DoNotOptimize(Tp& value) {
+  asm volatile("" : "+r,m"(value) : : "memory");
+}