diff --git a/cmdline/cmdline_parser.h b/cmdline/cmdline_parser.h
index cfc0967..d82fd48 100644
--- a/cmdline/cmdline_parser.h
+++ b/cmdline/cmdline_parser.h
@@ -390,7 +390,7 @@
         // Unlike regular argument definitions, when a value gets parsed into its
         // stronger type, we just throw it away.
 
-        if (ign.find("_") != std::string::npos) {  // Does the arg-def have a wildcard?
+        if (ign.find('_') != std::string::npos) {  // Does the arg-def have a wildcard?
           // pretend this is a string, e.g. -Xjitconfig:<anythinggoeshere>
           auto&& builder = Define(ignore_name).template WithType<std::string>().IntoIgnore();
           assert(&builder == this);