1 files changed, 19 insertions, 2 deletions
diff --git a/lib/pure/concurrency/cpuinfo.nim b/lib/pure/concurrency/cpuinfo.nim
index 603fee080..f01488811 100644
--- a/lib/pure/concurrency/cpuinfo.nim
+++ b/lib/pure/concurrency/cpuinfo.nim
@@ -45,8 +45,25 @@ proc countProcessors*(): int {.rtl, extern: "ncpi$1".} =
   ## returns the numer of the processors/cores the machine has.
   ## Returns 0 if it cannot be detected.
   when defined(windows):
-    var x = getEnv("NUMBER_OF_PROCESSORS")
-    if x.len > 0: result = parseInt(x.string)
+    type
+      SYSTEM_INFO {.final, pure.} = object
+        u1: int32
+        dwPageSize: int32
+        lpMinimumApplicationAddress: pointer
+        lpMaximumApplicationAddress: pointer
+        dwActiveProcessorMask: ptr int32
+        dwNumberOfProcessors: int32
+        dwProcessorType: int32
+        dwAllocationGranularity: int32
+        wProcessorLevel: int16
+        wProcessorRevision: int16
+
+    proc GetSystemInfo(lpSystemInfo: var SYSTEM_INFO) {.stdcall, dynlib: "kernel32", importc: "GetSystemInfo".}
+
+    var
+      si: SYSTEM_INFO
+    GetSystemInfo(si)
+    result = si.dwNumberOfProcessors
   elif defined(macosx) or defined(bsd):
     var
       mib: array[0..3, cint]