diff --git a/pkg/obiformats/options.go b/pkg/obiformats/options.go
index 6666e3c..030037f 100644
--- a/pkg/obiformats/options.go
+++ b/pkg/obiformats/options.go
@@ -64,7 +64,7 @@ func MakeOptions(setters []WithOption) Options {
 		csv_keys:              make([]string, 0),
 		csv_auto:              false,
 		paired_filename:       "",
-		source:                "",
+		source:                "unknown",
 		with_feature_table:    false,
 	}
 
diff --git a/pkg/obikmer/debruijn.go b/pkg/obikmer/debruijn.go
index a4b968f..1436d34 100644
--- a/pkg/obikmer/debruijn.go
+++ b/pkg/obikmer/debruijn.go
@@ -315,7 +315,7 @@ func (g *DeBruijnGraph) Weight(index uint64) int {
 	return int(val)
 }
 
-func (graph *DeBruijnGraph) append(sequence []byte, current uint64) {
+func (graph *DeBruijnGraph) append(sequence []byte, current uint64, weight int) {
 
 	for i := 0; i < len(sequence); i++ {
 		current <<= 2
@@ -323,14 +323,14 @@ func (graph *DeBruijnGraph) append(sequence []byte, current uint64) {
 		b := iupac[sequence[i]]
 		if len(b) == 1 {
 			current |= b[0]
-			graph.graph[current] = uint(graph.Weight(current) + 1)
+			graph.graph[current] = uint(graph.Weight(current) + weight)
 		} else {
 			for j := 0; j < len(b); j++ {
 				current &= ^uint64(3)
 				current |= b[j]
 
-				graph.graph[current] = uint(graph.Weight(current) + 1)
-				graph.append(sequence[(i+1):], current)
+				graph.graph[current] = uint(graph.Weight(current) + weight)
+				graph.append(sequence[(i+1):], current, weight)
 			}
 			return
 		}
@@ -341,6 +341,7 @@ func (graph *DeBruijnGraph) append(sequence []byte, current uint64) {
 func (graph *DeBruijnGraph) Push(sequence *obiseq.BioSequence) {
 	key := uint64(0)
 	s := sequence.Sequence()
+	w := sequence.Count()
 	init := make([]uint64, 0, 16)
 	var f func(start int, key uint64)
 	f = func(start int, key uint64) {
@@ -365,7 +366,7 @@ func (graph *DeBruijnGraph) Push(sequence *obiseq.BioSequence) {
 		f(0, key)
 
 		for _, idx := range init {
-			graph.append(s[graph.kmersize:], idx)
+			graph.append(s[graph.kmersize:], idx, w)
 		}
 	}
 }
diff --git a/pkg/obitools/obiconsensus/obiconsensus.go b/pkg/obitools/obiconsensus/obiconsensus.go
index 39d4176..d02ece8 100644
--- a/pkg/obitools/obiconsensus/obiconsensus.go
+++ b/pkg/obitools/obiconsensus/obiconsensus.go
@@ -99,9 +99,19 @@ func BuildConsensus(seqs obiseq.BioSequenceSlice,
 		}
 	}
 
-	seq, err := graph.LongestConsensus(seqs[0].Source())
+	id := seqs[0].Source()
+	if id == "" {
+		id = seqs[0].Id()
+	}
+	seq, err := graph.LongestConsensus(id)
 
-	seq.SetCount(len(seqs))
+	sumCount := 0
+
+	for _, s := range seqs {
+		sumCount += s.Count()
+	}
+
+	seq.SetCount(sumCount)
 	seq.SetAttribute("seq_length", seq.Len())
 	seq.SetAttribute("kmer_size", kmer_size)
 	seq.SetAttribute("kmer_min_occur", threshold)