diff --git a/flow/IndexedSet.cpp b/flow/IndexedSet.cpp
index 4c646fc38f..2065fabac0 100644
--- a/flow/IndexedSet.cpp
+++ b/flow/IndexedSet.cpp
@@ -252,6 +252,8 @@ TEST_CASE("performance/map/int/StdMap") {
 }
 
 TEST_CASE("performance/flow/IndexedSet/integers") {
+	std::mt19937_64 urng(deterministicRandom()->randomUInt32());
+
 	std::vector<int> x;
 	for (int i = 0; i<1000000; i++)
 		x.push_back(deterministicRandom()->randomInt(0, 10000000));
@@ -306,7 +308,7 @@ TEST_CASE("performance/flow/IndexedSet/integers") {
 
 	is.testonly_assertBalanced();
 
-	std::random_shuffle(x.begin(), x.end());
+	std::shuffle(x.begin(), x.end(), urng);
 	start = timer();
 	for (int i = 0; i<x.size(); i++) {
 		is.erase(x[i]);
diff --git a/flow/TreeBenchmark.h b/flow/TreeBenchmark.h
index 0189804315..746e45d718 100644
--- a/flow/TreeBenchmark.h
+++ b/flow/TreeBenchmark.h
@@ -23,6 +23,7 @@
 #pragma once
 
 #include "flow/flow.h"
+#include <random>
 
 struct opTimer {
 	double start = timer();
@@ -78,6 +79,8 @@ struct MapHarness {
 
 template <typename T, typename F>
 void treeBenchmark(T& tree, F generateKey) {
+	std::mt19937_64 urng(deterministicRandom()->randomUInt32());
+
 	using key = typename T::key_type;
 
 	int keyCount = 1000000;
@@ -105,7 +108,7 @@ void treeBenchmark(T& tree, F generateKey) {
 
 	timedRun("find (sorted)", keys, [&tree](key const& k) { ASSERT(tree.find(k) != tree.end()); });
 
-	std::random_shuffle(keys.begin(), keys.end());
+	std::shuffle(keys.begin(), keys.end(), urng);
 
 	timedRun("erase", keys, [&tree](key const& k) { tree.erase(k); });
 	ASSERT(tree.begin() == tree.end());