diff --git a/bundles/org.openhab.voice.picotts/src/main/java/org/openhab/voice/picotts/internal/PicoTTSService.java b/bundles/org.openhab.voice.picotts/src/main/java/org/openhab/voice/picotts/internal/PicoTTSService.java
index ecb6a2ebb..93d149c64 100644
--- a/bundles/org.openhab.voice.picotts/src/main/java/org/openhab/voice/picotts/internal/PicoTTSService.java
+++ b/bundles/org.openhab.voice.picotts/src/main/java/org/openhab/voice/picotts/internal/PicoTTSService.java
@@ -12,7 +12,6 @@
  */
 package org.openhab.voice.picotts.internal;
 
-import java.util.Collections;
 import java.util.Locale;
 import java.util.Set;
 import java.util.stream.Collectors;
@@ -49,8 +48,8 @@ public class PicoTTSService extends AbstractCachedTTSService {
                     new PicoTTSVoice("es-ES"), new PicoTTSVoice("fr-FR"), new PicoTTSVoice("it-IT"))
             .collect(Collectors.toSet());
 
-    private final Set<AudioFormat> audioFormats = Collections.singleton(
-            new AudioFormat(AudioFormat.CONTAINER_WAVE, AudioFormat.CODEC_PCM_SIGNED, false, 16, null, 16000L));
+    private final Set<AudioFormat> audioFormats = Set
+            .of(new AudioFormat(AudioFormat.CONTAINER_WAVE, AudioFormat.CODEC_PCM_SIGNED, false, 16, null, 16000L));
 
     @Override
     public Set<Voice> getAvailableVoices() {