diff --git a/jemalloc/configure.ac b/jemalloc/configure.ac
index b613cb1..0ed1373 100644
--- a/jemalloc/configure.ac
+++ b/jemalloc/configure.ac
@@ -166,7 +166,7 @@
   *-*-darwin*)
 	CFLAGS="$CFLAGS -fno-common -no-cpp-precomp"
 	abi="macho"
-	AC_DEFINE([JEMALLOC_PURGE_MSYNC_KILLPAGES])
+	AC_DEFINE([JEMALLOC_PURGE_MADVISE_FREE])
 	RPATH=""
 	;;
   *-*-freebsd*)
diff --git a/jemalloc/include/jemalloc/jemalloc_defs.h.in b/jemalloc/include/jemalloc/jemalloc_defs.h.in
index 54e5d94..b8f3f36 100644
--- a/jemalloc/include/jemalloc/jemalloc_defs.h.in
+++ b/jemalloc/include/jemalloc/jemalloc_defs.h.in
@@ -121,15 +121,12 @@
  *   madvise(..., MADV_DONTNEED) : On Linux, this immediately discards pages,
  *                                 such that new pages will be demand-zeroed if
  *                                 the address region is later touched.
- *   madvise(..., MADV_FREE) : On FreeBSD, this marks pages as being unused,
- *                             such that they will be discarded rather than
- *                             swapped out.
- *   msync(..., MS_KILLPAGES) : On Darwin, this behaves similarly to
- *                              madvise(..., MADV_FREE) on FreeBSD.
+ *   madvise(..., MADV_FREE) : On FreeBSD and Darwin, this marks pages as being
+ *                             unused, such that they will be discarded rather
+ *                             than swapped out.
  */
 #undef JEMALLOC_PURGE_MADVISE_DONTNEED
 #undef JEMALLOC_PURGE_MADVISE_FREE
-#undef JEMALLOC_PURGE_MSYNC_KILLPAGES
 
 /* sizeof(void *) == 2^LG_SIZEOF_PTR. */
 #undef LG_SIZEOF_PTR
diff --git a/jemalloc/src/arena.c b/jemalloc/src/arena.c
index 00f425f..3d4f888 100644
--- a/jemalloc/src/arena.c
+++ b/jemalloc/src/arena.c
@@ -800,9 +800,6 @@
 #elif defined(JEMALLOC_PURGE_MADVISE_FREE)
 		madvise((void *)((uintptr_t)chunk + (pageind << PAGE_SHIFT)),
 		    (npages << PAGE_SHIFT), MADV_FREE);
-#elif defined(JEMALLOC_PURGE_MSYNC_KILLPAGES)
-		msync((void *)((uintptr_t)chunk + (pageind << PAGE_SHIFT)),
-		    (npages << PAGE_SHIFT), MS_KILLPAGES);
 #else
 #  error "No method defined for purging unused dirty pages."
 #endif