no uniqueCounter it is

lib/pure/math.nim

@@ -188,11 +188,10 @@ when not defined(ECMAScript):
   proc rand(): cint {.importc: "rand", nodecl.}
   proc drand48(): float {.importc: "drand48", nodecl.}
     
-  var uniqueCounter: int = 0
   proc randomize() =
-    srand(gettime(nil) + cint(uniqueCounter))
-    srand48(gettime(nil) + cint(uniqueCounter))
-    atomicInc(uniqueCounter)
+    let x = gettime(nil)
+    srand(x)
+    srand48(x)
   proc random(max: int): int =
     result = int(rand()) mod max
   proc random(max: float): float =

tests/run/tmath.nim

@@ -5,11 +5,10 @@ import sets
 suite "random int":
   test "there might be some randomness":
     var set = initSet[int](128)
-    for i in 1..10:
-      for j in 1..10:
-        randomize()
-        incl(set, random(high(int)))
-    check len(set) == 100
+    randomize()
+    for i in 1..1000:
+      incl(set, random(high(int)))
+    check len(set) == 1000
   test "single number bounds work":
     randomize()
     var rand: int