diff --git a/tests/tools/test_memory_tool_import_fallback.py b/tests/tools/test_memory_tool_import_fallback.py
new file mode 100644
index 0000000000..a2550b8947
--- /dev/null
+++ b/tests/tools/test_memory_tool_import_fallback.py
@@ -0,0 +1,31 @@
+"""Regression tests for memory-tool import fallbacks."""
+
+import builtins
+import importlib
+import sys
+
+from tools.registry import registry
+
+
+def test_memory_tool_imports_without_fcntl(monkeypatch, tmp_path):
+    original_import = builtins.__import__
+
+    def fake_import(name, globals=None, locals=None, fromlist=(), level=0):
+        if name == "fcntl":
+            raise ImportError("simulated missing fcntl")
+        return original_import(name, globals, locals, fromlist, level)
+
+    registry.deregister("memory")
+    monkeypatch.delitem(sys.modules, "tools.memory_tool", raising=False)
+    monkeypatch.setattr(builtins, "__import__", fake_import)
+
+    memory_tool = importlib.import_module("tools.memory_tool")
+    monkeypatch.setattr(memory_tool, "get_memory_dir", lambda: tmp_path)
+
+    store = memory_tool.MemoryStore(memory_char_limit=200, user_char_limit=200)
+    store.load_from_disk()
+    result = store.add("memory", "fact learned during import fallback test")
+
+    assert memory_tool.fcntl is None
+    assert registry.get_entry("memory") is not None
+    assert result["success"] is True
diff --git a/tools/memory_tool.py b/tools/memory_tool.py
index 3e250bea40..7968c4aa9b 100644
--- a/tools/memory_tool.py
+++ b/tools/memory_tool.py
@@ -23,7 +23,6 @@ Design:
 - Frozen snapshot pattern: system prompt is stable, tool responses show live state
 """
 
-import fcntl
 import json
 import logging
 import os
@@ -34,6 +33,16 @@ from pathlib import Path
 from hermes_constants import get_hermes_home
 from typing import Dict, Any, List, Optional
 
+try:
+    import fcntl
+except ImportError:
+    fcntl = None
+
+try:
+    import msvcrt
+except ImportError:
+    msvcrt = None
+
 logger = logging.getLogger(__name__)
 
 # Where memory files live — resolved dynamically so profile overrides
@@ -139,12 +148,31 @@ class MemoryStore:
         """
         lock_path = path.with_suffix(path.suffix + ".lock")
         lock_path.parent.mkdir(parents=True, exist_ok=True)
-        fd = open(lock_path, "w")
+
+        if fcntl is None and msvcrt is None:
+            yield
+            return
+
+        if msvcrt and (not lock_path.exists() or lock_path.stat().st_size == 0):
+            lock_path.write_text(" ", encoding="utf-8")
+
+        fd = open(lock_path, "r+" if msvcrt else "a+")
         try:
-            fcntl.flock(fd, fcntl.LOCK_EX)
+            if fcntl:
+                fcntl.flock(fd, fcntl.LOCK_EX)
+            else:
+                fd.seek(0)
+                msvcrt.locking(fd.fileno(), msvcrt.LK_LOCK, 1)
             yield
         finally:
-            fcntl.flock(fd, fcntl.LOCK_UN)
+            if fcntl:
+                fcntl.flock(fd, fcntl.LOCK_UN)
+            elif msvcrt:
+                try:
+                    fd.seek(0)
+                    msvcrt.locking(fd.fileno(), msvcrt.LK_UNLCK, 1)
+                except (OSError, IOError):
+                    pass
             fd.close()
 
     @staticmethod