diff --git a/src/core/math.c b/src/core/math.c
index b945a4d8..c7424253 100644
--- a/src/core/math.c
+++ b/src/core/math.c
@@ -141,8 +141,7 @@ JANET_CORE_FN(cfun_rng_make,
 
 JANET_CORE_FN(cfun_rng_uniform,
               "(math/rng-uniform rng)",
-              "Extract a random random integer in the range [0, max] from the RNG. If "
-              "no max is given, the default is 2^31 - 1."
+              "Extract a random number in the range [0, 1) from the RNG."
              ) {
     janet_fixarity(argc, 1);
     JanetRNG *rng = janet_getabstract(argv, 0, &janet_rng_type);
diff --git a/src/core/os.c b/src/core/os.c
index 467830b5..a712b413 100644
--- a/src/core/os.c
+++ b/src/core/os.c
@@ -84,7 +84,6 @@ time_t timegm(struct tm *tm);
  * setenv/getenv are not thread safe. */
 #ifdef JANET_THREADS
 # ifdef JANET_WINDOWS
-static int env_lock_initialized = 0;
 static CRITICAL_SECTION env_lock;
 static void janet_lock_environ(void) {
     EnterCriticalSection(&env_lock);
@@ -2146,10 +2145,17 @@ void janet_lib_os(JanetTable *env) {
 #if !defined(JANET_REDUCED_OS) && defined(JANET_WINDOWS) && defined(JANET_THREADS)
     /* During start up, the top-most abstract machine (thread)
      * in the thread tree sets up the critical section. */
-    if (!env_lock_initialized) {
-        InitializeCriticalSection(&env_lock);
-        env_lock_initialized = 1;
+    static volatile long env_lock_initializing = 0;
+    static volatile long env_lock_initialized = 0;
+    if(!InterlockedExchange(&env_lock_initializing, 1)){
+      InitializeCriticalSection(&env_lock);
+      InterlockedOr(&env_lock_initialized, 1);
+    } else {
+      while (!InterlockedOr(&env_lock_initialized, 0)) {
+        Sleep(0);
+      }
     }
+
 #endif
 #ifndef JANET_NO_PROCESSES
 #endif