diff --git a/src/mozilla_taskgraph/worker_types.py b/src/mozilla_taskgraph/worker_types.py
index 7749a9b..77b7e18 100644
--- a/src/mozilla_taskgraph/worker_types.py
+++ b/src/mozilla_taskgraph/worker_types.py
@@ -73,7 +73,7 @@
 )
 def build_bitrise_payload(config, task, task_def):
     bitrise = task["worker"]["bitrise"]
-    build_params = task_def["payload"] = bitrise.get("build_params") or {}
+    build_params = bitrise.get("build_params") or {}
     task_def["tags"]["worker-implementation"] = "scriptworker"
 
     scope_prefix = config.graph_config["scriptworker"]["scope-prefix"]
@@ -104,6 +104,8 @@ def build_bitrise_payload(config, task, task_def):
                 "branch_dest_repo_owner", config.params["base_repository"]
             )
 
+    task_def["payload"] = {"build_params": build_params}
+
 
 @payload_builder(
     "scriptworker-shipit",
diff --git a/test/test_worker_types.py b/test/test_worker_types.py
index 993d75a..da8d636 100644
--- a/test/test_worker_types.py
+++ b/test/test_worker_types.py
@@ -21,9 +21,11 @@
             {},
             {
                 "payload": {
-                    "branch": "default",
-                    "branch_repo_owner": "http://example.com/head/repo",
-                    "commit_hash": "abcdef",
+                    "build_params": {
+                        "branch": "default",
+                        "branch_repo_owner": "http://example.com/head/repo",
+                        "commit_hash": "abcdef",
+                    },
                 },
                 "scopes": [
                     "foo:bitrise:app:some-app",
@@ -39,12 +41,14 @@
             {"tasks_for": "github-pull-request"},
             {
                 "payload": {
-                    "branch": "default",
-                    "branch_dest": "123456",
-                    "branch_dest_repo_owner": "http://example.com/base/repo",
-                    "branch_repo_owner": "http://example.com/head/repo",
-                    "commit_hash": "abcdef",
-                    "pull_request_author": "some-owner",
+                    "build_params": {
+                        "branch": "default",
+                        "branch_dest": "123456",
+                        "branch_dest_repo_owner": "http://example.com/base/repo",
+                        "branch_repo_owner": "http://example.com/head/repo",
+                        "commit_hash": "abcdef",
+                        "pull_request_author": "some-owner",
+                    },
                 },
                 "scopes": ["foo:bitrise:app:some-app", "foo:bitrise:workflow:bar"],
                 "tags": {"worker-implementation": "scriptworker"},
@@ -62,10 +66,12 @@
             },
             {
                 "payload": {
-                    "branch_repo_owner": "http://example.com/head/repo",
-                    "commit_hash": "abcdef",
-                    "pull_request_author": "some-owner",
-                    "tag": "some-tag",
+                    "build_params": {
+                        "branch_repo_owner": "http://example.com/head/repo",
+                        "commit_hash": "abcdef",
+                        "pull_request_author": "some-owner",
+                        "tag": "some-tag",
+                    }
                 },
                 "scopes": ["foo:bitrise:app:some-app", "foo:bitrise:workflow:bar"],
                 "tags": {"worker-implementation": "scriptworker"},