diff --git a/scripts/ivas_conformance/runConformance.py b/scripts/ivas_conformance/runConformance.py
index b69659880487583514c7439325172c2756826a18..6ee1b0f2979336d6425ba31c6fda8cd41ab7b5d1 100644
--- a/scripts/ivas_conformance/runConformance.py
+++ b/scripts/ivas_conformance/runConformance.py
@@ -38,7 +38,7 @@ import subprocess
 import tempfile
 import sys
 from typing import Tuple
-from multiprocessing import Pool
+from multiprocessing import Pool, Lock
 from dataclasses import dataclass
 from typing import Union
 import shutil
@@ -50,6 +50,7 @@ import filecmp
 
 sys.path.append(os.path.join(os.path.dirname(os.path.abspath(__file__)), ".."))
 
+mldLock = Lock()
 
 def readfile(
     filename: str, nchannels: int = 1, fs: int = 48000, outdtype="float"
@@ -849,8 +850,11 @@ class MLDConformance:
                     np.array([f"{pytestTag}-FRM{x}" for x in range(mldThisFile.size)]),
                 )
             )
-            with open(self.mldcsv[tag], "ab") as f:
-                np.savetxt(f, mldWithTags, fmt="%s", delimiter=",")
+            global mldLock
+            with mldLock:
+                with open(self.mldcsv[tag], "ab") as f:
+                    np.savetxt(f, mldWithTags, fmt="%s", delimiter=",")
+
             with open(self.sampleStats[tag], "a") as f:
                 f.write(
                     f"{pytestTag}, {maxDiff}, {rmsdB}, {beSamplesPercent}, {mldThisFile.max()}\n"