diff --git a/Riot/Modules/Room/VoiceMessages/VoiceMessageAttachmentCacheManager.swift b/Riot/Modules/Room/VoiceMessages/VoiceMessageAttachmentCacheManager.swift
index 1054c8232..f1fd66efd 100644
--- a/Riot/Modules/Room/VoiceMessages/VoiceMessageAttachmentCacheManager.swift
+++ b/Riot/Modules/Room/VoiceMessages/VoiceMessageAttachmentCacheManager.swift
@@ -23,6 +23,7 @@ enum VoiceMessageAttachmentCacheManagerError: Error {
     case decryptionError(Error)
     case preparationError(Error)
     case conversionError(Error)
+    case invalidNumberOfSamples
     case samplingError
 }
 
@@ -52,33 +53,32 @@ class VoiceMessageAttachmentCacheManager {
     }
     
     func loadAttachment(_ attachment: MXKAttachment, numberOfSamples: Int, completion: @escaping (Result<(URL, [Float]), Error>) -> Void) {
-        workQueue.async {
-            self.enqueueLoadAttachment(attachment, numberOfSamples: numberOfSamples, completion: completion)
-        }
-    }
-    
-    func enqueueLoadAttachment(_ attachment: MXKAttachment, numberOfSamples: Int, completion: @escaping (Result<(URL, [Float]), Error>) -> Void) {
         guard attachment.type == MXKAttachmentTypeVoiceMessage else {
-            DispatchQueue.main.async {
-                completion(Result.failure(VoiceMessageAttachmentCacheManagerError.invalidAttachmentType))
-            }
+            completion(Result.failure(VoiceMessageAttachmentCacheManagerError.invalidAttachmentType))
             return
         }
         
         guard let identifier = attachment.eventId else {
-            DispatchQueue.main.async {
-                completion(Result.failure(VoiceMessageAttachmentCacheManagerError.invalidEventId))
-            }
+            completion(Result.failure(VoiceMessageAttachmentCacheManagerError.invalidEventId))
+            return
+        }
+        
+        guard numberOfSamples > 0 else {
+            completion(Result.failure(VoiceMessageAttachmentCacheManagerError.invalidNumberOfSamples))
             return
         }
         
         if let finalURL = finalURLs[identifier], let samples = samples[identifier]?[numberOfSamples] {
-            DispatchQueue.main.async {
-                completion(Result.success((finalURL, samples)))
-            }
+            completion(Result.success((finalURL, samples)))
             return
         }
         
+        workQueue.async {
+            self.enqueueLoadAttachment(attachment, identifier: identifier, numberOfSamples: numberOfSamples, completion: completion)
+        }
+    }
+    
+    private func enqueueLoadAttachment(_ attachment: MXKAttachment, identifier: String, numberOfSamples: Int, completion: @escaping (Result<(URL, [Float]), Error>) -> Void) {
         if var callbacks = completionCallbacks[identifier] {
             callbacks.append(CompletionWrapper(completion))
             completionCallbacks[identifier] = callbacks
@@ -160,13 +160,14 @@ class VoiceMessageAttachmentCacheManager {
             return
         }
         
-        for wrapper in callbacks {
-            DispatchQueue.main.async {
+        let copy = callbacks.map { $0 }
+        DispatchQueue.main.async {
+            for wrapper in copy {
                 wrapper.completion(Result.success((url, samples)))
             }
         }
         
-        completionCallbacks[identifier] = nil
+        self.completionCallbacks[identifier] = nil
     }
     
     private func invokeFailureCallbacksForIdentifier(_ identifier: String, error: Error) {
@@ -174,12 +175,13 @@ class VoiceMessageAttachmentCacheManager {
             return
         }
         
-        for wrapper in callbacks {
-            DispatchQueue.main.async {
+        let copy = callbacks.map { $0 }
+        DispatchQueue.main.async {
+            for wrapper in copy {
                 wrapper.completion(Result.failure(error))
             }
         }
         
-        completionCallbacks[identifier] = nil
+        self.completionCallbacks[identifier] = nil
     }
 }
diff --git a/Riot/Modules/Room/VoiceMessages/VoiceMessageController.swift b/Riot/Modules/Room/VoiceMessages/VoiceMessageController.swift
index 1b072e445..3f8a61a12 100644
--- a/Riot/Modules/Room/VoiceMessages/VoiceMessageController.swift
+++ b/Riot/Modules/Room/VoiceMessages/VoiceMessageController.swift
@@ -300,7 +300,7 @@ public class VoiceMessageController: NSObject, VoiceMessageToolbarViewDelegate,
         displayLink.isPaused = !audioPlayer.isPlaying
         
         let requiredNumberOfSamples = _voiceMessageToolbarView.getRequiredNumberOfSamples()
-        if audioSamples.count != requiredNumberOfSamples {
+        if audioSamples.count != requiredNumberOfSamples  && requiredNumberOfSamples > 0 {
             padSamplesArrayToSize(requiredNumberOfSamples)
             
             waveformAnalyser = WaveformAnalyzer(audioAssetURL: url)