diff --git a/dom/chrome-webidl/PrioEncoder.webidl b/dom/chrome-webidl/PrioEncoder.webidl
index 58ff5a21157f..1dd00920cc9c 100644
--- a/dom/chrome-webidl/PrioEncoder.webidl
+++ b/dom/chrome-webidl/PrioEncoder.webidl
@@ -11,9 +11,7 @@ namespace PrioEncoder {
 };
 
 dictionary PrioParams {
-  required boolean browserIsUserDefault;
-  required boolean newTabPageEnabled;
-  required boolean pdfViewerUsed;
+  required sequence<boolean> booleans;
 };
 
 dictionary PrioEncodedData {
diff --git a/dom/prio/PrioEncoder.cpp b/dom/prio/PrioEncoder.cpp
index a700628d4a8c..bd4038b70ac2 100644
--- a/dom/prio/PrioEncoder.cpp
+++ b/dom/prio/PrioEncoder.cpp
@@ -105,13 +105,9 @@ PrioEncoder::Encode(GlobalObject& aGlobal,
     ClearOnShutdown(&sSingleton);
   }
 
-  bool dataItems[] = {
-    aPrioParams.mBrowserIsUserDefault,
-    aPrioParams.mNewTabPageEnabled,
-    aPrioParams.mPdfViewerUsed,
-  };
+  nsTArray<bool> dataItems = aPrioParams.mBooleans;
 
-  PrioConfig prioConfig = PrioConfig_new(mozilla::ArrayLength(dataItems),
+  PrioConfig prioConfig = PrioConfig_new(dataItems.Length(),
                                          sPublicKeyA,
                                          sPublicKeyB,
                                          reinterpret_cast<const unsigned char*>(aBatchID.BeginReading()),
@@ -132,7 +128,7 @@ PrioEncoder::Encode(GlobalObject& aGlobal,
   unsigned int lenB = 0;
 
   prio_rv = PrioClient_encode(prioConfig,
-                              dataItems,
+                              dataItems.Elements(),
                               &forServerA,
                               &lenA,
                               &forServerB,
diff --git a/dom/prio/test/gtest/TestPrioEncoder.cpp b/dom/prio/test/gtest/TestPrioEncoder.cpp
index d174afac2cc0..304a03da5e4c 100644
--- a/dom/prio/test/gtest/TestPrioEncoder.cpp
+++ b/dom/prio/test/gtest/TestPrioEncoder.cpp
@@ -28,10 +28,6 @@ TEST(PrioEncoder, BadPublicKeys)
   nsCString batchID = NS_LITERAL_CSTRING("abc123");
 
   mozilla::dom::PrioParams prioParams;
-  prioParams.mBrowserIsUserDefault = true;
-  prioParams.mNewTabPageEnabled = true;
-  prioParams.mPdfViewerUsed = false;
-
   mozilla::dom::RootedDictionary<mozilla::dom::PrioEncodedData> prioEncodedData(cx);
   mozilla::ErrorResult rv;
 
@@ -172,9 +168,11 @@ TEST(PrioEncoder, VerifyFull)
   batchID = (char*)(batchIDStr);
 
   mozilla::dom::PrioParams prioParams;
-  prioParams.mBrowserIsUserDefault = dataItems[0];
-  prioParams.mNewTabPageEnabled = dataItems[1];
-  prioParams.mPdfViewerUsed = dataItems[2];
+  FallibleTArray<bool> sequence;
+  *(sequence.AppendElement(mozilla::fallible)) = dataItems[0];
+  *(sequence.AppendElement(mozilla::fallible)) = dataItems[1];
+  *(sequence.AppendElement(mozilla::fallible)) = dataItems[2];
+  prioParams.mBooleans.Assign(sequence);
 
   mozilla::dom::RootedDictionary<mozilla::dom::PrioEncodedData> prioEncodedData(cx);
   mozilla::ErrorResult rv;