diff --git a/annotation/labelme_to_mrcnn.py b/annotation/labelme_to_mrcnn.py
index 6bf88c76e4d676db496040a730be1d3b9d1a7b02..4240a589ae5effac1d61f66f3cb9f0822895777a 100644
--- a/annotation/labelme_to_mrcnn.py
+++ b/annotation/labelme_to_mrcnn.py
@@ -287,7 +287,7 @@ if __name__ == '__main__':
             superclass = opt.classes[k]
             writedata['categories'].append({"supercategory": superclass, "id": (k+1), "name": superclass})
 
-        annotation_id = 0
+        annotation_id = 1   ## see: https://github.com/cocodataset/cocoapi/issues/507
 
         for j in tqdm(range (len(images))):
             imgname = images[j]
@@ -361,4 +361,4 @@ print("")
 if status == "successful":
     print("Conversion finished!")
 else:
-    print("Unfortunately, the conversion could not be done!")
\ No newline at end of file
+    print("Unfortunately, the conversion could not be done!")
diff --git a/annotation/labelme_to_orcnn.py b/annotation/labelme_to_orcnn.py
index 959c1a49be6445b8f35c1386224bcb45e9d8cfe9..b1144260850a5983b8acec417f7fc66f21fa0eb6 100644
--- a/annotation/labelme_to_orcnn.py
+++ b/annotation/labelme_to_orcnn.py
@@ -300,7 +300,7 @@ if __name__ == '__main__':
             superclass = opt.classes[k]
             writedata['categories'].append({"supercategory": superclass, "id": (k+1), "name": superclass})
 
-        annotation_id = 0
+        annotation_id = 1   ## see: https://github.com/cocodataset/cocoapi/issues/507
 
         for j in tqdm(range (len(images))):
             imgname = images[j]
@@ -367,4 +367,4 @@ print("")
 if status == "successful":
     print("Conversion finished!")
 else:
-    print("Unfortunately, the conversion could not be done...")
\ No newline at end of file
+    print("Unfortunately, the conversion could not be done...")