diff --git a/vpnor/test/write_rw.cpp b/vpnor/test/write_rw.cpp
index 1ee5c6c..1c4bd38 100644
--- a/vpnor/test/write_rw.cpp
+++ b/vpnor/test/write_rw.cpp
@@ -47,7 +47,7 @@
     rc = write_flash(ctx, 0x1000, src, sizeof(src));
     assert(rc == 0);
     fd = open((root.rw() / "TEST1").c_str(), O_RDONLY);
-    map = mmap(NULL, sizeof(src), PROT_READ, MAP_PRIVATE, fd, 0);
+    map = mmap(NULL, sizeof(src), PROT_READ, MAP_SHARED, fd, 0);
     assert(map != MAP_FAILED);
     rc = memcmp(src, map, sizeof(src));
     assert(rc == 0);