diff --git a/file_system.go b/file_system.go
index 1cddaad..a0253ad 100644
--- a/file_system.go
+++ b/file_system.go
@@ -244,7 +244,9 @@ type FileSystem interface {
 	//
 	// Note that one potentially significant case where this is *not* called is
 	// munmap(2). (Cf. http://goo.gl/7n1r9X, fuse-devel mailing list thread from
-	// Han-Wen Nienhuys on 2014-10-08.)
+	// Han-Wen Nienhuys on 2014-10-08.) Even if users close(2) after writing to
+	// an mmap'd file, on OS X the contents are not immediately flushed (cf.
+	// https://github.com/osxfuse/osxfuse/issues/202).
 	//
 	// Because of cases like dup2(2), calls to FlushFile are not necessarily one
 	// to one with calls to OpenFile. They should not be used for reference
diff --git a/samples/flushfs/flush_fs_test.go b/samples/flushfs/flush_fs_test.go
index 7cd3b2f..2421ede 100644
--- a/samples/flushfs/flush_fs_test.go
+++ b/samples/flushfs/flush_fs_test.go
@@ -614,13 +614,19 @@ func (t *FlushFSTest) Mmap_MunmapBeforeClose() {
 	ExpectThat(t.getFlushes(), ElementsAre())
 	ExpectThat(t.getFsyncs(), ElementsAre())
 
-	// Close the file. We should see a flush.
+	// Close the file. We should see a flush. On Darwin, this will contain out of
+	// date contents (cf. https://github.com/osxfuse/osxfuse/issues/202).
 	err = t.f1.Close()
 	t.f1 = nil
 	AssertEq(nil, err)
 
-	AssertThat(t.getFlushes(), ElementsAre("paco"))
-	AssertThat(t.getFsyncs(), ElementsAre())
+	if runtime.GOOS == "darwin" {
+		ExpectThat(t.getFlushes(), ElementsAre("taco"))
+		ExpectThat(t.getFsyncs(), ElementsAre())
+	} else {
+		ExpectThat(t.getFlushes(), ElementsAre("paco"))
+		ExpectThat(t.getFsyncs(), ElementsAre())
+	}
 }
 
 func (t *FlushFSTest) Mmap_CloseBeforeMunmap() {