diff --git a/spacy/tokens/doc.pyx b/spacy/tokens/doc.pyx
index cc7be7e74..bde0719ab 100644
--- a/spacy/tokens/doc.pyx
+++ b/spacy/tokens/doc.pyx
@@ -465,7 +465,7 @@ cdef class Doc:
             cdef int i
             for i in range(self.length):
                 self.c[i].ent_type = 0
-                self.c[i].ent_iob = 2  # Means O. Non-O are set from ents.
+                self.c[i].ent_iob = 0  # Means missing.
             cdef attr_t ent_type
             cdef int start, end
             for ent_info in ents: