diff --git a/bundles/org.openhab.voice.googletts/src/main/java/org/openhab/voice/googletts/internal/GoogleTTSService.java b/bundles/org.openhab.voice.googletts/src/main/java/org/openhab/voice/googletts/internal/GoogleTTSService.java
index d03e72c8d0d2e..13810f78bc63e 100644
--- a/bundles/org.openhab.voice.googletts/src/main/java/org/openhab/voice/googletts/internal/GoogleTTSService.java
+++ b/bundles/org.openhab.voice.googletts/src/main/java/org/openhab/voice/googletts/internal/GoogleTTSService.java
@@ -136,8 +136,8 @@ protected void activate(Map<String, Object> config) {
     @Deactivate
     protected void dispose() {
         apiImpl.dispose();
-        audioFormats.clear();
-        allVoices.clear();
+        audioFormats = new HashSet<>();
+        allVoices = new HashSet<>();
     }
 
     /**