diff --git a/alphapose/utils/vis.py b/alphapose/utils/vis.py
index 8eacbba5..fa78db90 100644
--- a/alphapose/utils/vis.py
+++ b/alphapose/utils/vis.py
@@ -96,7 +96,7 @@ def vis_frame_dense(frame, im_res, add_bbox=False, format='coco'):
             cv2.rectangle(img, (int(bbox[0]), int(bbox[2])), (int(bbox[1]), int(bbox[3])), BLUE, 2)
             # Draw indexes of humans
             if 'idx' in human.keys():
-                cv2.putText(img, ''.join(str(e) for e in human['idx']), (int(bbox[0]), int((bbox[2] + 26))), DEFAULT_FONT, 1, BLACK, 2)
+                cv2.putText(img, ''.join(str(human['idx'])), (int(bbox[0]), int((bbox[2] + 26))), DEFAULT_FONT, 1, BLACK, 2)
         # Draw keypoints
         for n in range(kp_scores.shape[0]):
             if kp_scores[n] <= 0.35:
@@ -167,7 +167,7 @@ def vis_frame_fast(frame, im_res, add_bbox=False, format='coco'):
             cv2.rectangle(img, (int(bbox[0]), int(bbox[2])), (int(bbox[1]), int(bbox[3])), BLUE, 2)
             # Draw indexes of humans
             if 'idx' in human.keys():
-                cv2.putText(img, ''.join(str(e) for e in human['idx']), (int(bbox[0]), int((bbox[2] + 26))), DEFAULT_FONT, 1, BLACK, 2)
+                cv2.putText(img, ''.join(str(human['idx'])), (int(bbox[0]), int((bbox[2] + 26))), DEFAULT_FONT, 1, BLACK, 2)
         # Draw keypoints
         for n in range(kp_scores.shape[0]):
             if kp_scores[n] <= 0.35:
@@ -245,7 +245,7 @@ def vis_frame(frame, im_res, add_bbox=False, format='coco'):
             # Draw indexes of humans
             if 'idx' in human.keys():
                 bg = img.copy()
-                cv2.putText(bg, ''.join(str(e) for e in human['idx']), (int(bbox[0] / 2), int((bbox[2] + 26) / 2)), DEFAULT_FONT, 0.5, BLACK, 1)
+                cv2.putText(bg, ''.join(str(human['idx'])), (int(bbox[0] / 2), int((bbox[2] + 26) / 2)), DEFAULT_FONT, 0.5, BLACK, 1)
                 transparency = 0.8
                 img = cv2.addWeighted(bg, transparency, img, 1 - transparency, 0)
         # Draw keypoints
diff --git a/docs/INSTALL.md b/docs/INSTALL.md
index 7fe74ed3..14c7061d 100644
--- a/docs/INSTALL.md
+++ b/docs/INSTALL.md
@@ -50,6 +50,9 @@ python setup.py build develop --user
 ```
 
 #### Windows
+Windows users should install Visual Studio due to the problem mentioned [here](https://github.com/MVIG-SJTU/AlphaPose/blob/master/setup.py#L121).
+If you do not want to install Visual Studio and want to use AlphaPose, you can refer to our [previous version](https://github.com/MVIG-SJTU/AlphaPose/tree/pytorch#installation) that do not require Visual Studio.
+
 For Windows user, if you meet error with PyYaml, you can download and install it manually from here: https://pyyaml.org/wiki/PyYAML.
 If your OS platform is `Windows`, make sure that Windows C++ build tool like visual studio 15+ or visual c++ 2015+ is installed for training.
 
@@ -99,4 +102,4 @@ Download and extract them under `./data`, and make them look like this:
             |-- 036645665.jpg
             |-- 045572740.jpg
             |-- ... 
-```
\ No newline at end of file
+```
diff --git a/setup.py b/setup.py
index 09edf805..d0980945 100644
--- a/setup.py
+++ b/setup.py
@@ -118,42 +118,41 @@ def make_cuda_ext(name, module, sources):
 
 def get_ext_modules():
     ext_modules = []
-    # only windows visual studio 2013~2017 support compile c/cuda extensions
+    # only windows visual studio 2013+ support compile c/cuda extensions
     # If you force to compile extension on Windows and ensure appropriate visual studio
     # is intalled, you can try to use these ext_modules.
-    if platform.system() != 'Windows':
-        ext_modules = [
-            make_cython_ext(
-                name='soft_nms_cpu',
-                module='detector.nms',
-                sources=['src/soft_nms_cpu.pyx']),
-            make_cuda_ext(
-                name='nms_cpu',
-                module='detector.nms',
-                sources=['src/nms_cpu.cpp']),
-            make_cuda_ext(
-                name='nms_cuda',
-                module='detector.nms',
-                sources=['src/nms_cuda.cpp', 'src/nms_kernel.cu']),
-            make_cuda_ext(
-                name='roi_align_cuda',
-                module='alphapose.utils.roi_align',
-                sources=['src/roi_align_cuda.cpp', 'src/roi_align_kernel.cu']),
-            make_cuda_ext(
-                name='deform_conv_cuda',
-                module='alphapose.models.layers.dcn',
-                sources=[
-                    'src/deform_conv_cuda.cpp',
-                    'src/deform_conv_cuda_kernel.cu'
-                ]),
-            make_cuda_ext(
-                name='deform_pool_cuda',
-                module='alphapose.models.layers.dcn',
-                sources=[
-                    'src/deform_pool_cuda.cpp',
-                    'src/deform_pool_cuda_kernel.cu'
-                ]),
-        ]
+    ext_modules = [
+        make_cython_ext(
+            name='soft_nms_cpu',
+            module='detector.nms',
+            sources=['src/soft_nms_cpu.pyx']),
+        make_cuda_ext(
+            name='nms_cpu',
+            module='detector.nms',
+            sources=['src/nms_cpu.cpp']),
+        make_cuda_ext(
+            name='nms_cuda',
+            module='detector.nms',
+            sources=['src/nms_cuda.cpp', 'src/nms_kernel.cu']),
+        make_cuda_ext(
+            name='roi_align_cuda',
+            module='alphapose.utils.roi_align',
+            sources=['src/roi_align_cuda.cpp', 'src/roi_align_kernel.cu']),
+        make_cuda_ext(
+            name='deform_conv_cuda',
+            module='alphapose.models.layers.dcn',
+            sources=[
+                'src/deform_conv_cuda.cpp',
+                'src/deform_conv_cuda_kernel.cu'
+            ]),
+        make_cuda_ext(
+            name='deform_pool_cuda',
+            module='alphapose.models.layers.dcn',
+            sources=[
+                'src/deform_pool_cuda.cpp',
+                'src/deform_pool_cuda_kernel.cu'
+            ]),
+    ]
     return ext_modules