diff --git a/scripts/fix_test.py b/scripts/fix_test.py
index 53b10d638..49a2e1870 100644
--- a/scripts/fix_test.py
+++ b/scripts/fix_test.py
@@ -15,12 +15,11 @@ How to use:
 """
 
 import argparse
-import ast
-import itertools
-import platform
 import sys
 from pathlib import Path
 
+from lib_updater import apply_patches, PatchSpec, UtMethod
+
 
 def parse_args():
     parser = argparse.ArgumentParser(description="Fix test.")
@@ -102,39 +101,16 @@ def path_to_test(path) -> list[str]:
     return parts[-2:]  # Get class name and method name
 
 
-def find_test_lineno(file: str, test: list[str]) -> tuple[int, int] | None:
-    """Find the line number and column offset of a test function.
-    Returns (lineno, col_offset) or None if not found.
-    """
-    a = ast.parse(file)
-    for key, node in ast.iter_fields(a):
-        if key == "body":
-            for n in node:
-                match n:
-                    case ast.ClassDef():
-                        if len(test) == 2 and test[0] == n.name:
-                            for fn in n.body:
-                                match fn:
-                                    case ast.FunctionDef() | ast.AsyncFunctionDef():
-                                        if fn.name == test[-1]:
-                                            return (fn.lineno, fn.col_offset)
-                    case ast.FunctionDef() | ast.AsyncFunctionDef():
-                        if n.name == test[0] and len(test) == 1:
-                            return (n.lineno, n.col_offset)
-    return None
-
-
-def apply_modifications(file: str, modifications: list[tuple[int, int]]) -> str:
-    """Apply all modifications in reverse order to avoid line number offset issues."""
-    lines = file.splitlines()
-    fixture = "@unittest.expectedFailure"
-    # Sort by line number in descending order
-    modifications.sort(key=lambda x: x[0], reverse=True)
-    for lineno, col_offset in modifications:
-        indent = " " * col_offset
-        lines.insert(lineno - 1, indent + fixture)
-        lines.insert(lineno - 1, indent + "# TODO: RUSTPYTHON")
-    return "\n".join(lines)
+def build_patches(test_parts_set: set[tuple[str, str]]) -> dict:
+    """Convert failing tests to lib_updater patch format."""
+    patches = {}
+    for class_name, method_name in test_parts_set:
+        if class_name not in patches:
+            patches[class_name] = {}
+        patches[class_name][method_name] = [
+            PatchSpec(UtMethod.ExpectedFailure, None, "")
+        ]
+    return patches
 
 
 def run_test(test_name):
@@ -167,26 +143,21 @@ if __name__ == "__main__":
     tests = run_test(test_name)
     f = test_path.read_text(encoding="utf-8")
 
-    # Collect all modifications first (with deduplication for subtests)
-    modifications = []
+    # Collect failing tests (with deduplication for subtests)
     seen_tests = set()  # Track (class_name, method_name) to avoid duplicates
     for test in tests.tests:
         if test.result == "fail" or test.result == "error":
             test_parts = path_to_test(test.path)
-            test_key = tuple(test_parts)
-            if test_key in seen_tests:
-                continue  # Skip duplicate (same test, different subtest)
-            seen_tests.add(test_key)
-            location = find_test_lineno(f, test_parts)
-            if location:
-                print(f"Modifying test: {test.name} at line {location[0]}")
-                modifications.append(location)
-            else:
-                print(f"Warning: Could not find test: {test.name} ({test_parts})")
+            if len(test_parts) == 2:
+                test_key = tuple(test_parts)
+                if test_key not in seen_tests:
+                    seen_tests.add(test_key)
+                    print(f"Marking test: {test_parts[0]}.{test_parts[1]}")
 
-    # Apply all modifications in reverse order
-    if modifications:
-        f = apply_modifications(f, modifications)
+    # Apply patches using lib_updater
+    if seen_tests:
+        patches = build_patches(seen_tests)
+        f = apply_patches(f, patches)
         test_path.write_text(f, encoding="utf-8")
 
-    print(f"Modified {len(modifications)} tests")
+    print(f"Modified {len(seen_tests)} tests")