diff --git a/api_core/google/api_core/iam.py b/api_core/google/api_core/iam.py
index 2257616d9aec2..30be0a0facc7f 100644
--- a/api_core/google/api_core/iam.py
+++ b/api_core/google/api_core/iam.py
@@ -35,11 +35,11 @@
        },
        {
            "role": "roles/editor",
-           "members": "allAuthenticatedUsers"
+           "members": {"allAuthenticatedUsers"}
        },
        {
            "role": "roles/viewer",
-           "members": "allUsers"
+           "members": {"allUsers"}
            "condition": {
                "title": "requested_time",
                "description": "Requests made before 2021-01-01T00:00:00Z",