diff --git a/Python/getargs.c b/Python/getargs.c
index 23b91fd..15f9df93 100644
--- a/Python/getargs.c
+++ b/Python/getargs.c
@@ -255,7 +255,7 @@
 		}
 	}
 
-	if (*format != '\0' && !isalpha(Py_CHARMASK((*format))) &&
+	if (*format != '\0' && !isalpha(Py_CHARMASK(*format)) &&
 	    *format != '(' &&
 	    *format != '|' && *format != ':' && *format != ';') {
 		PyErr_Format(PyExc_SystemError,