diff --git a/fastlabel/converters.py b/fastlabel/converters.py
index 9b60598..ac66ede 100644
--- a/fastlabel/converters.py
+++ b/fastlabel/converters.py
@@ -260,13 +260,30 @@ def __get_coco_annotation_keypoints(keypoints: list, category_keypoints: list) -
         if keypoint["value"]
     }
     for category_key in category_keypoints:
-        value = keypoint_values.get(category_key, [0, 0, 0])
+        value = keypoint_values.get(category_key)
+        if not value:
+            coco_annotation_keypoints.extend([0, 0, 0])
+            continue
         # Adjust fastlabel data definition to coco format
         visibility = 2 if value[2] == 1 else 1
         coco_annotation_keypoints.extend([value[0], value[1], visibility])
     return coco_annotation_keypoints
 
 
+COCO_KEYPOINT_V_INDEX = 2
+
+
+def __get_coco_num_keypoints(keypoints: list) -> int:
+    # https://cocodataset.org/#format-data
+    if not keypoints:
+        return 0
+    num_keypoints = 0
+    for keypoint in keypoints:
+        if keypoint["value"]:
+            num_keypoints += 1
+    return num_keypoints
+
+
 def __get_coco_annotation(
     id_: int,
     points: list,
@@ -278,7 +295,7 @@ def __get_coco_annotation(
     rotation: int,
 ) -> dict:
     annotation = {}
-    annotation["num_keypoints"] = len(keypoints) if keypoints else 0
+    annotation["num_keypoints"] = __get_coco_num_keypoints(keypoints)
     annotation["keypoints"] = (
         __get_coco_annotation_keypoints(keypoints, category["keypoints"])
         if keypoints