diff --git a/cryptonite.cabal b/cryptonite.cabal
index b1c8a77..9c6401b 100644
--- a/cryptonite.cabal
+++ b/cryptonite.cabal
@@ -245,7 +245,7 @@ Library
   if arch(x86_64)
     CPP-options: -DARCH_X86_64
 
-  if flag(support_rdrand) && (arch(i386) || arch(x86_64))
+  if flag(support_rdrand) && (arch(i386) || arch(x86_64)) && !os(windows)
     CPP-options:    -DSUPPORT_RDRAND
     Other-modules:  Crypto.Random.Entropy.RDRand
     c-sources:      cbits/cryptonite_rdrand.c