diff --git a/CHANGES b/CHANGES
index feacd18373..03bafd02bf 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,6 @@
+5020.	[func]		RNG uses thread-local storage instead of locks, if
+			supported by platform. [GL #496]
+
 5019.	[cleanup]	A message is now logged when ixfr-from-differences is
 			set at zone level for an inline-signed zone. [GL #470]
 
diff --git a/lib/dns/tests/dnstest.c b/lib/dns/tests/dnstest.c
index 11f344838a..3761abc7f0 100644
--- a/lib/dns/tests/dnstest.c
+++ b/lib/dns/tests/dnstest.c
@@ -161,18 +161,19 @@ dns_test_begin(FILE *logfile, bool start_managers) {
 
 void
 dns_test_end(void) {
+	cleanup_managers();
+
 	if (dst_active) {
 		dst_lib_destroy();
 		dst_active = false;
 	}
 
-	cleanup_managers();
-
 	if (lctx != NULL)
 		isc_log_destroy(&lctx);
 
 	if (mctx != NULL)
 		isc_mem_destroy(&mctx);
+
 }
 
 /*
diff --git a/lib/isc/random.c b/lib/isc/random.c
index 63b84cd46f..3f49cb512f 100644
--- a/lib/isc/random.c
+++ b/lib/isc/random.c
@@ -62,14 +62,28 @@
  */
 #include "xoshiro128starstar.c"
 
+#if defined(HAVE_TLS)
+#if defined(HAVE_THREAD_LOCAL)
+static thread_local isc_once_t isc_random_once = ISC_ONCE_INIT;
+#elif defined(HAVE___THREAD)
+static __thread isc_once_t isc_random_once = ISC_ONCE_INIT;
+#elif defined(HAVE___DECLSPEC_THREAD)
+static __declspec( thread ) isc_once_t isc_random_once = ISC_ONCE_INIT;
+#else
+#error "Unknown method for defining a TLS variable!"
+#endif
+#else
 static isc_once_t isc_random_once = ISC_ONCE_INIT;
+#endif
 
 static void
 isc_random_initialize(void) {
 #if FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
 	memset(seed, 0, sizeof(seed));
 #else
-	isc_entropy_get(seed, sizeof(seed));
+	int useed[4] = {0,0,0,0};
+	isc_entropy_get(useed, sizeof(useed));
+	memcpy(seed, useed, sizeof(seed));
 #endif
 }
 
diff --git a/lib/isc/win32/include/isc/platform.h.in b/lib/isc/win32/include/isc/platform.h.in
index 7f2bdbfb6b..691ac00122 100644
--- a/lib/isc/win32/include/isc/platform.h.in
+++ b/lib/isc/win32/include/isc/platform.h.in
@@ -16,6 +16,11 @@
  ***** Platform-dependent defines.
  *****/
 
+#if _MSC_VER > 1400
+#define HAVE_TLS 1
+#define HAVE___DECLSPEC_THREAD 1
+#endif
+
 /*
  * Some compatibility cludges
  */
diff --git a/lib/isc/xoshiro128starstar.c b/lib/isc/xoshiro128starstar.c
index bff2e3ad38..fb71a24419 100644
--- a/lib/isc/xoshiro128starstar.c
+++ b/lib/isc/xoshiro128starstar.c
@@ -34,6 +34,21 @@
  *
  * The state must be seeded so that it is not everywhere zero.
  */
+#if defined(HAVE_TLS)
+#define _LOCK() {};
+#define _UNLOCK() {};
+
+#if defined(HAVE_THREAD_LOCAL)
+static thread_local uint32_t seed[4];
+#elif defined(HAVE___THREAD)
+static __thread uint32_t seed[4];
+#elif defined(HAVE___DECLSPEC_THREAD)
+static __declspec( thread ) uint32_t seed[4];
+#else
+#error "Unknown method for defining a TLS variable!"
+#endif
+
+#else
 #if defined(_WIN32) || defined(_WIN64)
 #include <windows.h>
 static volatile HANDLE _mutex = NULL;
@@ -61,16 +76,18 @@ static volatile HANDLE _mutex = NULL;
 
 #include <pthread.h>
 static pthread_mutex_t _mutex = PTHREAD_MUTEX_INITIALIZER;
-#define _LOCK()   pthread_mutex_lock(&_mutex)
-#define _UNLOCK() pthread_mutex_unlock(&_mutex)
+#define _LOCK()   RUNTIME_CHECK(pthread_mutex_lock(&_mutex)==0)
+#define _UNLOCK() RUNTIME_CHECK(pthread_mutex_unlock(&_mutex)==0)
 #endif /* defined(_WIN32) || defined(_WIN64) */
 
+static uint32_t seed[4];
+
+#endif /* defined(HAVE_TLS) */
+
 static inline uint32_t rotl(const uint32_t x, int k) {
 	return (x << k) | (x >> (32 - k));
 }
 
-static uint32_t seed[4];
-
 static inline uint32_t
 next(void) {
 	uint32_t result_starstar, t;
diff --git a/lib/ns/tests/nstest.c b/lib/ns/tests/nstest.c
index ccbe1f65a6..662426f75d 100644
--- a/lib/ns/tests/nstest.c
+++ b/lib/ns/tests/nstest.c
@@ -277,13 +277,13 @@ ns_test_begin(FILE *logfile, bool start_managers) {
 
 void
 ns_test_end(void) {
+	cleanup_managers();
+
 	if (dst_active) {
 		dst_lib_destroy();
 		dst_active = false;
 	}
 
-	cleanup_managers();
-
 	if (lctx != NULL)
 		isc_log_destroy(&lctx);