diff --git a/src/speccpu/x264.py b/src/speccpu/x264.py
index 1360e5c..2e95504 100644
--- a/src/speccpu/x264.py
+++ b/src/speccpu/x264.py
@@ -203,3 +203,18 @@ def perf_ref(x264_run, perf_output):
         ],
         cwd=x264_run,
     )
+
+
+def recompile_mc_src(mc_src: str, x264_build: Path, spec_env: Mapping[str, str]):
+    mc_path = get_mc_path(x264_build)
+    assert mc_path.exists()
+
+    # Write mc_src to mc_path, recompile it, and replace resulting exe
+    with open(mc_path, "w") as f:
+        f.write(mc_src)
+
+    # Recompile
+    recompiled_x264_path = recompile_mc(mc_path, x264_build, spec_env)
+    assert recompiled_x264_path.exists()
+    assert recompiled_x264_path.is_file()
+    return recompiled_x264_path
diff --git a/test/test_spec.py b/test/test_spec.py
index d9d044b..b3c8e65 100644
--- a/test/test_spec.py
+++ b/test/test_spec.py
@@ -1,9 +1,11 @@
 from pathlib import Path
 from unittest import mock
+from unittest.mock import mock_open, patch
 
 import pytest
 
 from speccpu import SPEC, check_bench_dir, find_build
+from speccpu.x264 import recompile_mc_src
 
 
 class TestFindBuild:
@@ -169,3 +171,98 @@ class TestCheckBenchDir:
         (bench_dir / "RUN").mkdir()
 
         assert check_bench_dir(bench_dir) is False
+
+
+@pytest.fixture
+def mock_build_path():
+    return Path("/mock/build/path")
+
+
+@pytest.fixture
+def mock_spec_env():
+    return {"CC": "gcc", "CFLAGS": "-O2"}
+
+
+@pytest.fixture
+def mock_mc_path(mock_build_path):
+    return Path("/mock/build/path/x264_src/common/mc.c")
+
+
+def test_recompile_mc_src(mock_build_path, mock_spec_env, mock_mc_path):
+    test_mc_src = "test source code"
+
+    with (
+        patch("speccpu.x264.get_mc_path", return_value=mock_mc_path) as mock_get_path,
+        patch("builtins.open", mock_open()) as mock_file,
+        patch("speccpu.x264.recompile_mc") as mock_recompile,
+        patch.object(Path, "exists", return_value=True),
+        patch.object(Path, "is_file", return_value=True),
+    ):
+
+        # Configure recompile_mc mock to return a path
+        mock_exe_path = Path("/mock/build/path/x264_s")
+        mock_recompile.return_value = mock_exe_path
+
+        # Call the function under test
+        result = recompile_mc_src(test_mc_src, mock_build_path, mock_spec_env)
+
+        # Verify the function behavior
+        mock_get_path.assert_called_once_with(mock_build_path)
+        mock_file.assert_called_once_with(mock_mc_path, "w")
+        mock_file().write.assert_called_once_with(test_mc_src)
+        mock_recompile.assert_called_once_with(
+            mock_mc_path, mock_build_path, mock_spec_env
+        )
+
+
+def test_recompile_mc_src_file_not_exists(mock_build_path, mock_spec_env, mock_mc_path):
+    test_mc_src = "test source code"
+
+    with (
+        patch("speccpu.x264.get_mc_path", return_value=mock_mc_path),
+        patch.object(Path, "exists", return_value=False),
+    ):
+
+        # Test that the function raises an assertion error when file doesn't exist
+        with pytest.raises(AssertionError):
+            recompile_mc_src(test_mc_src, mock_build_path, mock_spec_env)
+
+
+def test_recompile_mc_src_exe_not_exists(mock_build_path, mock_spec_env, mock_mc_path):
+    test_mc_src = "test source code"
+
+    with (
+        patch("speccpu.x264.get_mc_path", return_value=mock_mc_path) as mock_get_path,
+        patch("builtins.open", mock_open()) as mock_file,
+        patch("speccpu.x264.recompile_mc") as mock_recompile,
+        patch.object(Path, "exists", side_effect=[True, False]),
+        patch.object(Path, "is_file", return_value=True),
+    ):
+
+        # Configure recompile_mc mock to return a path
+        mock_exe_path = Path("/mock/build/path/x264_s")
+        mock_recompile.return_value = mock_exe_path
+
+        # Test that the function raises an assertion error when exe doesn't exist
+        with pytest.raises(AssertionError):
+            recompile_mc_src(test_mc_src, mock_build_path, mock_spec_env)
+
+
+def test_recompile_mc_src_exe_not_file(mock_build_path, mock_spec_env, mock_mc_path):
+    test_mc_src = "test source code"
+
+    with (
+        patch("speccpu.x264.get_mc_path", return_value=mock_mc_path) as mock_get_path,
+        patch("builtins.open", mock_open()) as mock_file,
+        patch("speccpu.x264.recompile_mc") as mock_recompile,
+        patch.object(Path, "exists", return_value=True),
+        patch.object(Path, "is_file", return_value=False),
+    ):
+
+        # Configure recompile_mc mock to return a path
+        mock_exe_path = Path("/mock/build/path/x264_s")
+        mock_recompile.return_value = mock_exe_path
+
+        # Test that the function raises an assertion error when exe is not a file
+        with pytest.raises(AssertionError):
+            recompile_mc_src(test_mc_src, mock_build_path, mock_spec_env)
diff --git a/tools/x264_disable_mc_mul.py b/tools/x264_disable_mc_mul.py
index 01e83ca..bfd8115 100644
--- a/tools/x264_disable_mc_mul.py
+++ b/tools/x264_disable_mc_mul.py
@@ -22,19 +22,9 @@ def x264_disable_mc_mul(
     assert x264_build.exists()
     assert "x264_src" in os.listdir(x264_build)
 
-    mc_path = x264.get_mc_path(x264_build)
-    assert mc_path.exists()
-
     mc_src = x264.MCBuilder().with_disabled_iscale_mul().build()
 
-    # Write mc_src to mc_path, recompile it, and replace resulting exe
-    with open(mc_path, "w") as f:
-        f.write(mc_src)
-
-    # Recompile
-    recompiled_x264_path = x264.recompile_mc(mc_path, x264_build, spec_env)
-    assert recompiled_x264_path.exists()
-    assert recompiled_x264_path.is_file()
+    recompiled_x264_path = x264.recompile_mc_src(mc_src, x264_build, spec_env)
 
     # Execute that new binary
     x264.update_exe(recompiled_x264_path, x264_dir / "exe")