diff --git a/dom/media/webspeech/synth/moz.build b/dom/media/webspeech/synth/moz.build
index 2cf19982b2..dcdcdb5cbf 100644
--- a/dom/media/webspeech/synth/moz.build
+++ b/dom/media/webspeech/synth/moz.build
@@ -63,3 +63,6 @@ FINAL_LIBRARY = "xul"
 LOCAL_INCLUDES += [
     "ipc",
 ]
+
+# DOM Mask
+LOCAL_INCLUDES += ['/omegacfg']
\ No newline at end of file
diff --git a/dom/media/webspeech/synth/nsSynthVoiceRegistry.cpp b/dom/media/webspeech/synth/nsSynthVoiceRegistry.cpp
index e5a1353d6b..4a4a5b080b 100644
--- a/dom/media/webspeech/synth/nsSynthVoiceRegistry.cpp
+++ b/dom/media/webspeech/synth/nsSynthVoiceRegistry.cpp
@@ -27,6 +27,7 @@
 
 #include "SpeechSynthesisChild.h"
 #include "SpeechSynthesisParent.h"
+#include "MaskConfig.hpp"
 
 using mozilla::intl::LocaleService;
 
@@ -169,6 +170,20 @@ nsSynthVoiceRegistry* nsSynthVoiceRegistry::GetInstance() {
       // Start up all speech synth services.
       NS_CreateServicesFromCategory(NS_SPEECH_SYNTH_STARTED, nullptr,
                                     NS_SPEECH_SYNTH_STARTED);
+      // Load voices from MaskConfig
+      if (auto voices = MaskConfig::MVoices()) {
+        for (const auto& [lang, name, uri, isDefault, isLocal] :
+             voices.value()) {
+          gSynthVoiceRegistry->AddVoiceImpl(
+              nullptr, NS_ConvertUTF8toUTF16(uri), NS_ConvertUTF8toUTF16(name),
+              NS_ConvertUTF8toUTF16(lang), isLocal,
+              false);  // queuesUtterances set to false
+          if (isDefault) {
+            gSynthVoiceRegistry->SetDefaultVoice(NS_ConvertUTF8toUTF16(uri),
+                                                 true);
+          }
+        }
+      }
     }
   }
 
@@ -305,6 +320,8 @@ nsSynthVoiceRegistry::AddVoice(nsISpeechService* aService,
     return NS_ERROR_NOT_AVAILABLE;
   }
 
+  if (MaskConfig::GetBool("voices:blockIfNotDefined")) return NS_OK;
+
   return AddVoiceImpl(aService, aUri, aName, aLang, aLocalService,
                       aQueuesUtterances);
 }
@@ -779,6 +796,35 @@ void nsSynthVoiceRegistry::SpeakImpl(VoiceData* aVoice, nsSpeechTask* aTask,
        NS_ConvertUTF16toUTF8(aText).get(),
        NS_ConvertUTF16toUTF8(aVoice->mUri).get(), aRate, aPitch));
 
+  // Check if this voice is in our MVoices config
+  if (auto voices = MaskConfig::MVoices()) {
+    for (const auto& [lang, name, uri, isDefault, isLocal] : voices.value()) {
+      if (NS_ConvertUTF8toUTF16(uri).Equals(aVoice->mUri)) {
+        printf_stderr("Tried to speak a fake voice: %s",
+                      NS_ConvertUTF16toUTF8(aVoice->mUri).get());
+        aTask->Init();
+        // If fake completion is disabled, throw an error
+        if (!MaskConfig::GetBool("voices:fakeCompletion")) {
+          aTask->DispatchError(0, 0);
+          return;
+        }
+        float charsPerSecond;
+        if (auto value =
+                MaskConfig::GetDouble("voices:fakeCompletion:charsPerSecond")) {
+          charsPerSecond = value.value();
+        } else {
+          charsPerSecond = 12.5f;
+        }
+        // Return a fake success with a speach rate of 150wpm
+        aTask->DispatchStart();
+        float fakeElapsedTime =
+            static_cast<float>(aText.Length()) / (charsPerSecond * aRate);
+        aTask->DispatchEnd(fakeElapsedTime, aText.Length());
+        return;
+      }
+    }
+  }
+
   aTask->Init();
 
   if (NS_FAILED(aVoice->mService->Speak(aText, aVoice->mUri, aVolume, aRate,