Index: ghc-8.0.1/rts/posix/OSMem.c
===================================================================
--- ghc-8.0.1.orig/rts/posix/OSMem.c
+++ ghc-8.0.1/rts/posix/OSMem.c
@@ -504,13 +504,7 @@ void osDecommitMemory(void *at, W_ size)
         sysErrorBelch("unable to make released memory unaccessible");
 #endif
 
-#ifdef MADV_FREE
-    // Try MADV_FREE first, FreeBSD has both and MADV_DONTNEED
-    // just swaps memory out
-    r = madvise(at, size, MADV_FREE);
-#else
     r = madvise(at, size, MADV_DONTNEED);
-#endif
     if(r < 0)
         sysErrorBelch("unable to decommit memory");
 }