--- src/acl/external/session/ext_session_acl.cc	2026-01-20 06:45:36.000000000 +0800
+++ src/acl/external/session/ext_session_acl.cc	2026-06-07 23:09:09.000000000 +0800
@@ -137,9 +137,15 @@
         }
     }
 #elif HAVE_LIBTDB
-#if _SQUID_FREEBSD_ && !defined(O_DSYNC)
-    // FreeBSD lacks O_DSYNC, O_SYNC is closest to correct behaviour
+#if !defined(O_DSYNC)
+    // O_SYNC is closest to correct behaviour
+#if defined(O_SYNC)
 #define O_DSYNC O_SYNC
+#elif defined(O_FSYNC)
+#define O_DSYNC O_FSYNC
+#else
+#define O_DSYNC 0
+#endif
 #endif
     db = tdb_open(db_path, 0, TDB_CLEAR_IF_FIRST, O_CREAT|O_DSYNC, 0666);
 #endif