diff --git a/passes/silimate/reg_rename.cc b/passes/silimate/reg_rename.cc
index 3cfd9e70b..6c67ef080 100644
--- a/passes/silimate/reg_rename.cc
+++ b/passes/silimate/reg_rename.cc
@@ -306,7 +306,7 @@ struct RegRenamePass : public Pass {
 						size_t open = signal_name.rfind('[');
 						if (open != std::string::npos) {
 							std::string inner = signal_name.substr(open + 1, signal_name.size() - open - 2);
-							// Ensure that signal_bits is not populated with non-digits
+							// Ensure that signal_bits is not populated with non-indexed characters.
 							if (!inner.empty() && inner.find_first_not_of("0123456789:") == std::string::npos) {
 								signal_bits = signal_name.substr(open);
 								signal_name.erase(open);