diff --git a/snap-server.cabal b/snap-server.cabal
index fe17d499..1a1ef812 100644
--- a/snap-server.cabal
+++ b/snap-server.cabal
@@ -72,6 +72,11 @@ Flag libev
     Description: Use libev?
     Default:     False
 
+Flag portable
+  Description: Compile in cross-platform mode. No platform-specific code or
+               optimizations such as C routines will be used.
+  Default: False
+
 
 Library
   hs-source-dirs: dist/build/autogen, src
@@ -111,7 +116,9 @@ Library
     unix-compat,
     vector >= 0.6 && <0.7
 
-  if !os(windows)
+  if flag(portable) || os(windows)
+    cpp-options: -DPORTABLE
+  else
     build-depends: unix
 
   if flag(libev)
@@ -130,9 +137,6 @@ Library
   if os(darwin)
     cpp-options: -DOSX
 
-  if os(windows)
-    cpp-options: -DWIN32
-
   ghc-prof-options: -prof -auto-all
 
   if impl(ghc >= 6.12.0)
diff --git a/src/Snap/Internal/Http/Server/Date.hs b/src/Snap/Internal/Http/Server/Date.hs
index 24612657..6d9b371b 100644
--- a/src/Snap/Internal/Http/Server/Date.hs
+++ b/src/Snap/Internal/Http/Server/Date.hs
@@ -14,7 +14,7 @@ import           Data.IORef
 import           Foreign.C.Types
 import           System.IO.Unsafe
 
-#ifndef WIN32
+#ifndef PORTABLE
 import           System.Posix.Time
 #else
 import           Data.Time.Clock.POSIX
@@ -60,7 +60,7 @@ dateState = unsafePerformIO $ do
     return d
 
 
-#ifdef WIN32
+#ifdef PORTABLE
 epochTime :: IO CTime
 epochTime = do
     t <- getPOSIXTime
diff --git a/test/snap-server-testsuite.cabal b/test/snap-server-testsuite.cabal
index b94928cf..ed5241eb 100644
--- a/test/snap-server-testsuite.cabal
+++ b/test/snap-server-testsuite.cabal
@@ -7,6 +7,11 @@ Flag libev
     Description: Use libev?
     Default:     False
 
+Flag portable
+  Description: Compile in cross-platform mode. No platform-specific code or
+               optimizations such as C routines will be used.
+  Default: False
+
 Executable testsuite
    hs-source-dirs:  ../src suite
    main-is:         TestSuite.hs
@@ -55,8 +60,8 @@ Executable testsuite
 
      other-modules: Snap.Internal.Http.Server.SimpleBackend
 
-   if os(windows)
-     cpp-options: -DWIN32
+   if flag(portable) || os(windows)
+     cpp-options: -DPORTABLE
 
    ghc-options: -O2 -Wall -fhpc -fwarn-tabs -funbox-strict-fields -threaded
                 -fno-warn-unused-do-bind
@@ -114,8 +119,8 @@ Executable pongserver
    if os(darwin)
      cpp-options: -DOSX
 
-   if os(windows)
-     cpp-options: -DWIN32
+   if flag(portable) || os(windows)
+     cpp-options: -DPORTABLE
 
    ghc-options: -Wall -O2 -fwarn-tabs -funbox-strict-fields -threaded
                 -fno-warn-unused-do-bind