diff --git a/automated_security_helper/utils/sarif_utils.py b/automated_security_helper/utils/sarif_utils.py
index 4db0feeb..c7ecf1e8 100644
--- a/automated_security_helper/utils/sarif_utils.py
+++ b/automated_security_helper/utils/sarif_utils.py
@@ -5,6 +5,8 @@
 from typing import List
 import uuid
 from pathlib import Path
+from urllib.request import url2pathname
+
 from automated_security_helper.base.plugin_context import PluginContext
 from automated_security_helper.core.constants import (
     ASH_WORK_DIR_NAME,
@@ -68,8 +70,8 @@ def _sanitize_uri(uri: str, source_dir_path: Path, source_dir_str: str) -> str:
         return uri
 
     # Remove file:// prefix if present
-    if uri.startswith("file://"):
-        uri = uri[7:]
+    if uri.startswith("file:"):
+        uri = url2pathname(uri[5:])
 
     # Make path relative to source directory
     try:
diff --git a/tests/unit/utils/test_sarif_utils.py b/tests/unit/utils/test_sarif_utils.py
index 2bb8bec2..67e79e16 100644
--- a/tests/unit/utils/test_sarif_utils.py
+++ b/tests/unit/utils/test_sarif_utils.py
@@ -1,10 +1,11 @@
-from pathlib import Path
 import sys
+from pathlib import Path
 from unittest.mock import patch
+from urllib.request import pathname2url
 
 from automated_security_helper.utils.sarif_utils import (
-    get_finding_id,
     _sanitize_uri,
+    get_finding_id,
     path_matches_pattern,
 )
 
@@ -33,7 +34,8 @@ def test_sanitize_uri(test_source_dir):
     source_dir_str = str(source_dir_path) + "/"
 
     # Test with file:// prefix - this should work without mocking
-    uri = f"file://{source_dir_path}/src/file.py"
+    uri = "file:" + pathname2url(f"{source_dir_path}/src/file.py")
+    assert uri.startswith("file://")
     with patch.object(Path, "relative_to", return_value=Path("src/file.py")):
         sanitized = _sanitize_uri(uri, source_dir_path, source_dir_str)
         # Use partial matching for the parts that don't involve path separators