diff --git a/libs/ardour/audiofilesource.cc b/libs/ardour/audiofilesource.cc
index fc9ca3cc70..13b08a53d4 100644
--- a/libs/ardour/audiofilesource.cc
+++ b/libs/ardour/audiofilesource.cc
@@ -184,7 +184,11 @@ AudioFileSource::construct_peak_filepath (const string& audio_path, const bool i
 		base = audio_path;
 	}
 	base += '%';
-	base += (char) ('A' + _channel);
+	if (_channel < 26) {
+		base += (char) ('A' + _channel);
+	} else {
+		base +=  string_compose ("%1", _channel + 1);
+	}
 	return _session.construct_peak_filepath (base, in_session, old_peak_name);
 }
 
diff --git a/libs/ardour/utils.cc b/libs/ardour/utils.cc
index ec526637ef..0d64d94376 100644
--- a/libs/ardour/utils.cc
+++ b/libs/ardour/utils.cc
@@ -323,9 +323,12 @@ ARDOUR::region_name_from_path (string path, bool strip_channels, bool add_channe
 
 	if (add_channel_suffix) {
 
+		/* compare to Session::format_audio_source_name */
 		path += '%';
 
-		if (total > 2) {
+		if (total > 25) {
+			path += string_compose ("%1", this_one + 1);
+		} else if (total > 2) {
 			path += (char) ('a' + this_one);
 		} else {
 			path += (char) (this_one == 0 ? 'L' : 'R');