diff --git a/warp.cabal b/warp.cabal
--- a/warp.cabal
+++ b/warp.cabal
@@ -1,5 +1,5 @@
 Name:                warp
-Version:             1.3.4.2
+Version:             1.3.4.3
 Synopsis:            A fast, light-weight web server for WAI applications.
 License:             MIT
 License-file:        LICENSE
@@ -82,12 +82,16 @@
                    , HUnit
                    , QuickCheck
                    , hspec                    == 1.3.*
-  if os(linux) || os(freebsd) || os(darwin)
-      Cpp-Options:   -DSENDFILEFD
-      Build-Depends: unix
+
+    -- Yes, this means that the test suite will no longer work on Windows.
+    -- Unfortunately there is a bug in older versions of cabal, and this conditional
+    -- will therefore break older systems.
+  --if os(linux) || os(freebsd) || os(darwin)
+    Cpp-Options:   -DSENDFILEFD
+    Build-Depends: unix
                    , hashable
-  if os(windows)
-      Cpp-Options:   -DWINDOWS
+  --if os(windows)
+  --    Cpp-Options:   -DWINDOWS
 
 Source-Repository head
   Type:     git