diff --git a/cpp/src/plasma/common.cc b/cpp/src/plasma/common.cc
index 2de06d5f8cf..be3fc74b062 100644
--- a/cpp/src/plasma/common.cc
+++ b/cpp/src/plasma/common.cc
@@ -17,6 +17,8 @@
 
 #include "plasma/common.h"
 
+#include <limits>
+#include <mutex>
 #include <random>
 
 #include "plasma/plasma_generated.h"
@@ -28,9 +30,15 @@ using arrow::Status;
 UniqueID UniqueID::from_random() {
   UniqueID id;
   uint8_t* data = id.mutable_data();
-  std::random_device engine;
+  // NOTE(pcm): The right way to do this is to have one std::mt19937 per
+  // thread (using the thread_local keyword), but that's not supported on
+  // older versions of macOS (see https://stackoverflow.com/a/29929949)
+  static std::mutex mutex;
+  std::lock_guard<std::mutex> lock(mutex);
+  static std::mt19937 generator;
+  std::uniform_int_distribution<uint32_t> dist(0, std::numeric_limits<uint8_t>::max());
   for (int i = 0; i < kUniqueIDSize; i++) {
-    data[i] = static_cast<uint8_t>(engine());
+    data[i] = static_cast<uint8_t>(dist(generator));
   }
   return id;
 }
diff --git a/cpp/src/plasma/test/client_tests.cc b/cpp/src/plasma/test/client_tests.cc
index b80862d95b4..23d2c2b1a53 100644
--- a/cpp/src/plasma/test/client_tests.cc
+++ b/cpp/src/plasma/test/client_tests.cc
@@ -51,8 +51,8 @@ class TestPlasmaStore : public ::testing::Test {
   // TODO(pcm): At the moment, stdout of the test gets mixed up with
   // stdout of the object store. Consider changing that.
   void SetUp() {
-    std::mt19937 rng;
-    rng.seed(std::random_device()());
+    uint64_t seed = std::chrono::high_resolution_clock::now().time_since_epoch().count();
+    std::mt19937 rng(static_cast<uint32_t>(seed));
     std::string store_index = std::to_string(rng());
     store_socket_name_ = "/tmp/store" + store_index;