diff --git a/python/obitools3/obidms/capi/obialign.pxd b/python/obitools3/obidms/capi/obialign.pxd
index e76cabe..c2280b9 100644
--- a/python/obitools3/obidms/capi/obialign.pxd
+++ b/python/obitools3/obidms/capi/obialign.pxd
@@ -18,7 +18,8 @@ cdef extern from "obi_align.h" nogil:
                                  double threshold, 
                                  bint normalize, 
                                  int reference, 
-                                 bint similarity_mode)
+                                 bint similarity_mode,
+                                 int thread_count)
 
 
     int obi_lcs_align_two_columns(OBIDMS_p dms,