diff --git a/analysis/concurrent_knowledge.py b/analysis/concurrent_knowledge.py
index 4706ac9..ee993a0 100644
--- a/analysis/concurrent_knowledge.py
+++ b/analysis/concurrent_knowledge.py
@@ -5,7 +5,6 @@
 vulnerability hypotheses, allowing multiple agents to collaborate on analysis.
 """
 
-import fcntl
 import hashlib
 import json
 import threading
@@ -17,6 +16,8 @@
 from pathlib import Path
 from typing import Any
 
+import portalocker
+
 # ============================================================================
 # Base Concurrent Store
 # ============================================================================
@@ -47,7 +48,7 @@ def _acquire_lock(self, timeout: float = 10.0) -> Any:
         
         while True:
             try:
-                fcntl.flock(lock_file, fcntl.LOCK_EX | fcntl.LOCK_NB)
+                portalocker.lock(lock_file, portalocker.LOCK_EX | portalocker.LOCK_NB)
                 return lock_file
             except OSError:
                 if time.time() - start_time > timeout:
@@ -58,7 +59,7 @@ def _acquire_lock(self, timeout: float = 10.0) -> Any:
     def _release_lock(self, lock_file: Any):
         """Release file lock."""
         try:
-            fcntl.flock(lock_file, fcntl.LOCK_UN)
+            portalocker.unlock(lock_file)
             lock_file.close()
             if self.lock_path.exists():
                 self.lock_path.unlink()
diff --git a/commands/project.py b/commands/project.py
index b7e4d3c..a0aacd6 100644
--- a/commands/project.py
+++ b/commands/project.py
@@ -225,8 +225,9 @@ def get_project(self, name: str) -> dict | None:
         if not config_file.exists():
             return None
         
-        import fcntl
         import time
+
+        import portalocker
         
         # Retry logic for reading JSON with file locking
         max_retries = 5
@@ -235,9 +236,9 @@ def get_project(self, name: str) -> dict | None:
                 with open(config_file) as f:
                     # Try to get a shared lock for reading
                     try:
-                        fcntl.flock(f.fileno(), fcntl.LOCK_SH | fcntl.LOCK_NB)
+                        portalocker.lock(f.fileno(), portalocker.LOCK_SH | portalocker.LOCK_NB)
                         content = f.read()
-                        fcntl.flock(f.fileno(), fcntl.LOCK_UN)
+                        portalocker.unlock(f.fileno())
                     except OSError:
                         # If we can't get lock, just read anyway
                         content = f.read()
@@ -266,9 +267,9 @@ def get_project(self, name: str) -> dict | None:
             with open(config_file, 'w') as f:
                 # Try to get exclusive lock for writing
                 try:
-                    fcntl.flock(f.fileno(), fcntl.LOCK_EX | fcntl.LOCK_NB)
+                    portalocker.lock(f.fileno(), portalocker.LOCK_EX | portalocker.LOCK_NB)
                     json.dump(config, f, indent=2)
-                    fcntl.flock(f.fileno(), fcntl.LOCK_UN)
+                    portalocker.unlock(f.fileno())
                 except OSError:
                     # If we can't get lock, skip updating last_accessed
                     pass
diff --git a/requirements.txt b/requirements.txt
index ad220cd..a53e2fc 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -13,7 +13,6 @@ typer>=0.9.0
 pydantic>=2.0.0
 pydantic-settings>=2.0
 pyyaml>=6.0
-
 # Async Support
 httpx>=0.25.0
 
@@ -26,3 +25,6 @@ scikit-learn>=1.3.0
 
 # CLI Enhancement
 rich>=13.0.0
+
+# File Locking
+portalocker>=2.7.0
\ No newline at end of file