diff --git a/src/taskgraph/generator.py b/src/taskgraph/generator.py
index 6951fb610..a944a8b02 100644
--- a/src/taskgraph/generator.py
+++ b/src/taskgraph/generator.py
@@ -100,9 +100,9 @@ def load_tasks(self, parameters, kind_dependencies_tasks, write_artifacts):
                 attributes=task_dict["attributes"],
                 task=task_dict["task"],
                 optimization=task_dict.get("optimization"),
-                dependencies=task_dict.get("dependencies"),
-                soft_dependencies=task_dict.get("soft-dependencies"),
-                if_dependencies=task_dict.get("if-dependencies"),
+                dependencies=task_dict.get("dependencies", {}),
+                soft_dependencies=task_dict.get("soft-dependencies", []),
+                if_dependencies=task_dict.get("if-dependencies", []),
             )
             for task_dict in transforms(trans_config, inputs)
         ]
diff --git a/src/taskgraph/task.py b/src/taskgraph/task.py
index cc401b9b6..b89fd6365 100644
--- a/src/taskgraph/task.py
+++ b/src/taskgraph/task.py
@@ -75,9 +75,9 @@ def from_json(cls, task_dict):
             attributes=task_dict["attributes"],
             task=task_dict["task"],
             optimization=task_dict["optimization"],
-            dependencies=task_dict.get("dependencies"),
-            soft_dependencies=task_dict.get("soft_dependencies"),
-            if_dependencies=task_dict.get("if_dependencies"),
+            dependencies=task_dict.get("dependencies", {}),
+            soft_dependencies=task_dict.get("soft_dependencies", []),
+            if_dependencies=task_dict.get("if_dependencies", []),
         )
         if "task_id" in task_dict:
             rv.task_id = task_dict["task_id"]