diff --git a/testing/web-platform/tests/interfaces/webauthn.idl b/testing/web-platform/tests/interfaces/webauthn.idl
index 562718086758..9de7f64919d6 100644
--- a/testing/web-platform/tests/interfaces/webauthn.idl
+++ b/testing/web-platform/tests/interfaces/webauthn.idl
@@ -115,8 +115,6 @@ dictionary AuthenticationExtensionsClientInputs {
 dictionary AuthenticationExtensionsClientOutputs {
 };
 
-typedef record<DOMString, DOMString> AuthenticationExtensionsAuthenticatorInputs;
-
 dictionary CollectedClientData {
     required DOMString           type;
     required DOMString           challenge;
@@ -192,6 +190,29 @@ partial dictionary AuthenticationExtensionsClientOutputs {
     CredentialPropertiesOutput credProps;
 };
 
+dictionary AuthenticationExtensionsPRFValues {
+    required ArrayBuffer first;
+    ArrayBuffer second;
+};
+
+dictionary AuthenticationExtensionsPRFInputs {
+    AuthenticationExtensionsPRFValues eval;
+    record<USVString, AuthenticationExtensionsPRFValues> evalByCredential;
+};
+
+partial dictionary AuthenticationExtensionsClientInputs {
+    AuthenticationExtensionsPRFInputs prf;
+};
+
+dictionary AuthenticationExtensionsPRFOutputs {
+    boolean enabled;
+    AuthenticationExtensionsPRFValues results;
+};
+
+partial dictionary AuthenticationExtensionsClientOutputs {
+    AuthenticationExtensionsPRFOutputs prf;
+};
+
 partial dictionary AuthenticationExtensionsClientInputs {
     AuthenticationExtensionsLargeBlobInputs largeBlob;
 };