diff --git a/.changeset/dirty-rings-cry.md b/.changeset/dirty-rings-cry.md
new file mode 100644
index 00000000000..d3fbefbbe51
--- /dev/null
+++ b/.changeset/dirty-rings-cry.md
@@ -0,0 +1,5 @@
+---
+'@firebase/functions': patch
+---
+
+Fixes a bug introduced in #3782 that causes callable functions to throw an error in browser extensions.
diff --git a/packages-exp/functions-exp/src/index.ts b/packages-exp/functions-exp/src/index.ts
index 3ebaeb7034a..ad8b299b634 100644
--- a/packages-exp/functions-exp/src/index.ts
+++ b/packages-exp/functions-exp/src/index.ts
@@ -21,5 +21,5 @@ import { name, version } from '../package.json';
 
 export * from './api';
 
-registerFunctions(fetch);
+registerFunctions(fetch.bind(self));
 registerVersion(name, version);
diff --git a/packages/functions/index.ts b/packages/functions/index.ts
index 1996574328d..24dbbdca2b2 100644
--- a/packages/functions/index.ts
+++ b/packages/functions/index.ts
@@ -21,7 +21,7 @@ import { registerFunctions } from './src/config';
 
 import { name, version } from './package.json';
 
-registerFunctions(firebase as _FirebaseNamespace, fetch);
+registerFunctions(firebase as _FirebaseNamespace, fetch.bind(self));
 firebase.registerVersion(name, version);
 
 declare module '@firebase/app-types' {