diff --git a/cppwg/__main__.py b/cppwg/__main__.py
index cf39d0e..0c7293c 100644
--- a/cppwg/__main__.py
+++ b/cppwg/__main__.py
@@ -6,6 +6,7 @@
 from pathlib import Path
 
 from cppwg import CppWrapperGenerator
+from cppwg.utils.constants import CPPWG_DEFAULT_LOGFILE
 from cppwg.version import __version__
 
 
@@ -132,7 +133,7 @@ def parse_args() -> argparse.Namespace:
         type=str,
         nargs="?",
         default=None,
-        const="cppwg.log",
+        const=CPPWG_DEFAULT_LOGFILE,
         help="Output log messages to a file.",
     )
 
diff --git a/cppwg/utils/constants.py b/cppwg/utils/constants.py
index 14ecc24..c52527b 100644
--- a/cppwg/utils/constants.py
+++ b/cppwg/utils/constants.py
@@ -6,6 +6,9 @@
 CPPWG_EXT = "cppwg"
 CPPWG_HEADER_COLLECTION_FILENAME = f"wrapper_header_collection.{CPPWG_EXT}.hpp"
 
+# Default log file name used when --logfile is passed without a value.
+CPPWG_DEFAULT_LOGFILE = f"{CPPWG_EXT}.log"
+
 CPPWG_TRUE_STRINGS = ["ON", "YES", "Y", "TRUE", "T", "1"]
 CPPWG_FALSE_STRINGS = ["OFF", "NO", "N", "FALSE", "F", "0", ""]