diff --git a/mmaction/models/builder.py b/mmaction/models/builder.py
index df95a94d40..f7316bd69a 100644
--- a/mmaction/models/builder.py
+++ b/mmaction/models/builder.py
@@ -13,7 +13,7 @@
     # Define an empty registry and building func, so that can import
     DETECTORS = Registry('detector')
 
-    def bulid_detector(cfg, train_cfg, test_cfg):
+    def build_detector(cfg, train_cfg, test_cfg):
         pass
 
 
diff --git a/mmaction/models/heads/roi_head.py b/mmaction/models/heads/roi_head.py
index f94aa85a6a..45a36df528 100644
--- a/mmaction/models/heads/roi_head.py
+++ b/mmaction/models/heads/roi_head.py
@@ -85,5 +85,5 @@ def simple_test_bboxes(self,
             return det_bboxes, det_labels
 else:
     # Just define an empty class, so that __init__ can import it.
-    class AVARoIHead(StandardRoIHead):
+    class AVARoIHead:
         pass
diff --git a/mmaction/models/roi_extractors/single_straight3d.py b/mmaction/models/roi_extractors/single_straight3d.py
index 09d40b1dcf..aafceeaf1d 100644
--- a/mmaction/models/roi_extractors/single_straight3d.py
+++ b/mmaction/models/roi_extractors/single_straight3d.py
@@ -2,7 +2,11 @@
 
 import torch
 import torch.nn as nn
-from mmcv.ops import RoIAlign, RoIPool
+
+try:
+    from mmcv.ops import RoIAlign, RoIPool
+except (ImportError, ModuleNotFoundError):
+    warnings.warn('Please install mmcv-full to use RoIAlign and RoIPool')
 
 try:
     import mmdet  # noqa