diff --git a/packages/taler-wallet-webextension/src/platform/chrome.ts b/packages/taler-wallet-webextension/src/platform/chrome.ts
index 99c0c134f..e56c0b3e9 100644
--- a/packages/taler-wallet-webextension/src/platform/chrome.ts
+++ b/packages/taler-wallet-webextension/src/platform/chrome.ts
@@ -271,6 +271,9 @@ function openWalletURIFromPopup(talerUri: string): void {
         `Response with HTTP 402 the Taler header but could not classify ${talerUri}`,
       );
       return;
+    case TalerUriType.TalerDevExperiment:
+      logger.warn(`taler://dev-experiment URIs are not allowed in headers`);
+      return;
     default: {
       const error: never = uriType;
       logger.warn(
diff --git a/packages/taler-wallet-webextension/src/wxBackend.ts b/packages/taler-wallet-webextension/src/wxBackend.ts
index 8689c92c7..1bb8ac332 100644
--- a/packages/taler-wallet-webextension/src/wxBackend.ts
+++ b/packages/taler-wallet-webextension/src/wxBackend.ts
@@ -301,6 +301,10 @@ function parseTalerUriAndRedirect(tabId: number, talerUri: string): void {
         `Response with HTTP 402 the Taler header but could not classify ${talerUri}`,
       );
       return;
+    case TalerUriType.TalerDevExperiment:
+      // FIXME: Implement!
+      logger.warn("not implemented");
+      return;
     default: {
       const error: never = uriType;
       logger.warn(