diff --git a/pkg/obioptions/version.go b/pkg/obioptions/version.go
index d06fd67..aa539bb 100644
--- a/pkg/obioptions/version.go
+++ b/pkg/obioptions/version.go
@@ -8,7 +8,7 @@ import (
 // corresponds to the last commit, and not the one when the file will be
 // commited
 
-var _Commit = "1c6ab1c"
+var _Commit = "efc3f3a"
 var _Version = "Release 4.4.0"
 
 // Version returns the version of the obitools package.
diff --git a/pkg/obiseq/merge.go b/pkg/obiseq/merge.go
index be598fa..15fa902 100644
--- a/pkg/obiseq/merge.go
+++ b/pkg/obiseq/merge.go
@@ -174,13 +174,14 @@ func (sequence *BioSequence) StatsPlusOne(desc StatsOnDescription, toAdd *BioSeq
 
 	}
 
+	dw := desc.Weight(toAdd)
 	sequence.annot_lock.Lock()
 	old, ok := stats[sval]
 	if !ok {
 		old = 0
 	}
 
-	stats[sval] = old + desc.Weight(toAdd)
+	stats[sval] = old + dw
 	sequence.annot_lock.Unlock()
 
 	sequence.SetAttribute(StatsOnSlotName(desc.Name), stats) // TODO: check if this is necessary