diff --git a/buildtools/gen-pmdinfo-cfile.py b/buildtools/gen-pmdinfo-cfile.py
index 58fe3ad152..5fbd51658a 100644
--- a/buildtools/gen-pmdinfo-cfile.py
+++ b/buildtools/gen-pmdinfo-cfile.py
@@ -9,12 +9,13 @@
 
 _, tmp_root, ar, archive, output, *pmdinfogen = sys.argv
 with tempfile.TemporaryDirectory(dir=tmp_root) as temp:
-    run_ar = lambda command: subprocess.run(
-        [ar, command, os.path.abspath(archive)],
-        stdout=subprocess.PIPE, check=True, cwd=temp
-    )
-    # Don't use "ar p", because its output is corrupted on Windows.
-    run_ar("x")
-    names = run_ar("t").stdout.decode().splitlines()
-    paths = [os.path.join(temp, name) for name in names]
+    paths = []
+    for name in subprocess.run([ar, "t", archive], stdout=subprocess.PIPE,
+                               check=True).stdout.decode().splitlines():
+        if os.path.exists(name):
+            paths.append(name)
+        else:
+            subprocess.run([ar, "x", os.path.abspath(archive), name],
+                           check=True, cwd=temp)
+            paths.append(os.path.join(temp, name))
     subprocess.run(pmdinfogen + paths + [output], check=True)