diff --git a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/session/content/ContentAttachmentData.kt b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/session/content/ContentAttachmentData.kt
index 38c3dd860c..7ee26de8db 100644
--- a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/session/content/ContentAttachmentData.kt
+++ b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/session/content/ContentAttachmentData.kt
@@ -36,7 +36,7 @@ data class ContentAttachmentData(
         val queryUri: Uri,
         val mimeType: String?,
         val type: Type,
-        val waveform: List<Int?>? = null
+        val waveform: List<Int>? = null
 ) : Parcelable {
 
     @JsonClass(generateAdapter = false)
diff --git a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/room/send/DefaultSendService.kt b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/room/send/DefaultSendService.kt
index a64b903947..6dbb71e096 100644
--- a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/room/send/DefaultSendService.kt
+++ b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/room/send/DefaultSendService.kt
@@ -185,7 +185,7 @@ internal class DefaultSendService @AssistedInject constructor(
                             name = messageContent.body,
                             queryUri = Uri.parse(messageContent.url),
                             type = ContentAttachmentData.Type.AUDIO,
-                            waveform = messageContent.audioWaveformInfo?.waveform
+                            waveform = messageContent.audioWaveformInfo?.waveform?.filterNotNull()
                     )
                     localEchoRepository.updateSendState(localEcho.eventId, roomId, SendState.UNSENT)
                     internalSendMedia(listOf(localEcho.root), attachmentData, true)
diff --git a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/room/send/WaveFormSanitizer.kt b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/room/send/WaveFormSanitizer.kt
index b0474dd6ff..78a03f3775 100644
--- a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/room/send/WaveFormSanitizer.kt
+++ b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/room/send/WaveFormSanitizer.kt
@@ -33,7 +33,7 @@ internal class WaveFormSanitizer @Inject constructor() {
      * The array should have no less than 30 elements and no more than 120.
      * List of integers between zero and 1024, inclusive.
      */
-    fun sanitize(waveForm: List<Int?>?): List<Int>? {
+    fun sanitize(waveForm: List<Int>?): List<Int>? {
         if (waveForm.isNullOrEmpty()) {
             return null
         }
@@ -46,7 +46,7 @@ internal class WaveFormSanitizer @Inject constructor() {
                 val repeatTimes = ceil(MIN_NUMBER_OF_VALUES / waveForm.size.toDouble()).toInt()
                 waveForm.map { value ->
                     repeat(repeatTimes) {
-                        sizeInRangeList.add(value ?: 0)
+                        sizeInRangeList.add(value)
                     }
                 }
             }
@@ -54,12 +54,12 @@ internal class WaveFormSanitizer @Inject constructor() {
                 val keepOneOf = ceil(waveForm.size.toDouble() / MAX_NUMBER_OF_VALUES).toInt()
                 waveForm.mapIndexed { idx, value ->
                     if (idx % keepOneOf == 0) {
-                        sizeInRangeList.add(value ?: 0)
+                        sizeInRangeList.add(value)
                     }
                 }
             }
             else                                 -> {
-                sizeInRangeList.addAll(waveForm.filterNotNull())
+                sizeInRangeList.addAll(waveForm)
             }
         }