diff --git a/tools/chplcheck/src/config.py b/tools/chplcheck/src/config.py
index 79d7be003e61..8bd456fe9703 100644
--- a/tools/chplcheck/src/config.py
+++ b/tools/chplcheck/src/config.py
@@ -114,7 +114,7 @@ def add_arguments(cls, parser: argparse.ArgumentParser, prefix: str = ""):
         )
         parser.add_argument(
             f"--{prefix}check-internal-prefix",
-            action="append",
+            action="store_true",
             dest="chplcheck_check_internal_prefixes",
             default=False,
             help="Check symbols with internal prefixes when linting",