diff --git a/contrib/ci/check-null-false-returns.py b/contrib/ci/check-null-false-returns.py
index 7502aa36d..48fbbe85b 100755
--- a/contrib/ci/check-null-false-returns.py
+++ b/contrib/ci/check-null-false-returns.py
@@ -225,6 +225,8 @@ def test_files():
     # test all C source files
     validator = ReturnValidator()
     for fn in glob.glob("**/*.c", recursive=True):
+        if fn.startswith("dist/") or fn.startswith("subprojects/"):
+            continue
         validator.parse(fn)
     for warning in validator.warnings:
         print(warning)