diff --git a/openhands/core/main.py b/openhands/core/main.py
index f2555766f8..43a07a02db 100644
--- a/openhands/core/main.py
+++ b/openhands/core/main.py
@@ -139,7 +139,7 @@ async def run_controller(
             selected_repository=config.sandbox.selected_repo,
             repo_directory=repo_directory,
             conversation_instructions=conversation_instructions,
-            working_dir=config.workspace_mount_path_in_sandbox,
+            working_dir=str(runtime.workspace_root),
         )
 
     # Add MCP tools to the agent
diff --git a/tests/unit/core/config/test_config.py b/tests/unit/core/config/test_config.py
index 8fcb7d2ee6..78abd5b804 100644
--- a/tests/unit/core/config/test_config.py
+++ b/tests/unit/core/config/test_config.py
@@ -443,6 +443,8 @@ def test_sandbox_volumes(monkeypatch, default_config):
         'SANDBOX_VOLUMES',
         '/host/path1:/container/path1,/host/path2:/container/path2:ro',
     )
+    # Clear any existing workspace mount path to test default behavior
+    monkeypatch.delenv('WORKSPACE_MOUNT_PATH_IN_SANDBOX', raising=False)
 
     load_from_env(default_config, os.environ)
     finalize_config(default_config)
@@ -465,6 +467,8 @@ def test_sandbox_volumes(monkeypatch, default_config):
 def test_sandbox_volumes_with_mode(monkeypatch, default_config):
     # Test SANDBOX_VOLUMES with read-only mode (no explicit /workspace mount)
     monkeypatch.setenv('SANDBOX_VOLUMES', '/host/path1:/container/path1:ro')
+    # Clear any existing workspace mount path to test default behavior
+    monkeypatch.delenv('WORKSPACE_MOUNT_PATH_IN_SANDBOX', raising=False)
 
     load_from_env(default_config, os.environ)
     finalize_config(default_config)
diff --git a/tests/unit/test_state_metrics_exposure.py b/tests/unit/test_state_metrics_exposure.py
index a6ec4b23e0..24b89eaefb 100644
--- a/tests/unit/test_state_metrics_exposure.py
+++ b/tests/unit/test_state_metrics_exposure.py
@@ -27,6 +27,7 @@ class FakeEventStream:
 class FakeRuntime:
     def __init__(self):
         self.event_stream = FakeEventStream()
+        self.workspace_root = '/workspace'
 
     async def connect(self):
         return None