diff --git a/src/opus.cc b/src/opus.cc
index c2bdb5d..d8dffea 100644
--- a/src/opus.cc
+++ b/src/opus.cc
@@ -122,28 +122,15 @@ ot::dynamic_ogg_packet ot::render_tags(const opus_tags& tags)
 	return op;
 }
 
-/**
- * \todo Make the field name case-insensitive?
- */
-static int match_field(const char *comment, uint32_t len, const char *field)
-{
-	size_t field_len;
-	for (field_len = 0; field[field_len] != '\0' && field[field_len] != '='; field_len++);
-	if (len <= field_len)
-		return 0;
-	if (comment[field_len] != '=')
-		return 0;
-	if (strncmp(comment, field, field_len) != 0)
-		return 0;
-	return 1;
-}
-
-void ot::delete_comments(opus_tags& tags, const char* field_name)
+void ot::delete_comments(opus_tags& tags, const std::string& field_name)
 {
+	auto field_len = field_name.size();
 	auto it = tags.comments.begin(), end = tags.comments.end();
 	while (it != end) {
 		auto current = it++;
-		if (match_field(current->data(), current->size(), field_name))
+		if (current->size() > field_len + 1 &&
+		    (*current)[field_len] == '=' &&
+		    strncmp(current->data(), field_name.data(), field_len) == 0)
 			tags.comments.erase(current);
 	}
 }
diff --git a/src/opustags.h b/src/opustags.h
index e859812..e6089b2 100644
--- a/src/opustags.h
+++ b/src/opustags.h
@@ -363,7 +363,7 @@ dynamic_ogg_packet render_tags(const opus_tags& tags);
  * \todo Move to module cli.
  * \todo Accept fields like X=Y to remove only comments X=Y, instead of all X.
  */
-void delete_comments(opus_tags& tags, const char* field_name);
+void delete_comments(opus_tags& tags, const std::string& field_name);
 
 /** \} */