diff --git a/data/config.py b/data/config.py
index 8999622cc..259739b56 100644
--- a/data/config.py
+++ b/data/config.py
@@ -27,7 +27,7 @@
 }
 
 coco = {
-    'num_classes': 201,
+    'num_classes': 21,
     'lr_steps': (280000, 360000, 400000),
     'max_iter': 400000,
     'feature_maps': [38, 19, 10, 5, 3, 1],