diff --git a/src/plugins/System/Plugins/Env.hs b/src/plugins/System/Plugins/Env.hs
index c5ddba4..fdee42f 100644
--- a/src/plugins/System/Plugins/Env.hs
+++ b/src/plugins/System/Plugins/Env.hs
@@ -353,7 +353,7 @@ classifyLdInput _ = return Nothing
 -- TODO need to define a MAC/DARWIN symbol
 #if defined(darwin_TARGET_OS)
 mkSOName root = "lib" ++ root ++ ".dylib"
-#if defined(CYGWIN) || defined(__MINGW32__)
+#elif defined(CYGWIN) || defined(__MINGW32__)
 -- Win32 DLLs have no .dll extension here, because addDLL tries
 -- both foo.dll and foo.drv
 mkSOName root = root