diff --git a/tools/check_source/check_deprecated.py b/tools/check_source/check_deprecated.py
index 0e2036acad6..0c1bd50649d 100644
--- a/tools/check_source/check_deprecated.py
+++ b/tools/check_source/check_deprecated.py
@@ -24,7 +24,7 @@ from os.path import splitext
 
 SKIP_DIRS = (
     "extern",
-    # Not this directory.
+    "lib",
     "tests",
 )