diff --git a/seqeval/metrics/sequence_labeling.py b/seqeval/metrics/sequence_labeling.py
index d642c90..175bd4a 100644
--- a/seqeval/metrics/sequence_labeling.py
+++ b/seqeval/metrics/sequence_labeling.py
@@ -53,10 +53,10 @@ def _validate_chunk(chunk, suffix):
 
         if suffix:
             tag = chunk[-1]
-            type_ = chunk.split('-')[0]
+            type_ = chunk[:-1].rsplit('-', maxsplit=1)[0] or '_'
         else:
             tag = chunk[0]
-            type_ = chunk.split('-')[-1]
+            type_ = chunk[1:].split('-', maxsplit=1)[-1] or '_'
 
         if end_of_chunk(prev_tag, tag, prev_type, type_):
             chunks.append((prev_type, begin_offset, i-1))