diff --git a/src/store/journal.c b/src/store/journal.c
index f7f82aa2..53ea0ad9 100644
--- a/src/store/journal.c
+++ b/src/store/journal.c
@@ -173,7 +173,11 @@ ray_err_t ray_journal_write_bytes(const ray_ipc_header_t* hdr,
 #ifndef RAY_OS_WINDOWS
         if (fsync(fileno(g_journal.fp)) != 0) return RAY_ERR_IO;
 #else
-        FlushFileBuffers((HANDLE)_get_osfhandle(_fileno(g_journal.fp)));
+        /* FlushFileBuffers returns 0 (FALSE) on failure — surface it as an I/O
+         * error like the fsync path above, so SYNC mode's durability guarantee
+         * isn't silently dropped on Windows. */
+        if (!FlushFileBuffers((HANDLE)_get_osfhandle(_fileno(g_journal.fp))))
+            return RAY_ERR_IO;
 #endif
     }
     return RAY_OK;