diff --git a/Release-notes.md b/Release-notes.md
index 87cc731..ad79c6c 100644
--- a/Release-notes.md
+++ b/Release-notes.md
@@ -6,6 +6,8 @@
 
 - In `obicsv` the **--keep count** was not equivalent to **--count**.
 - In `obipairing` and `obipcrtag` correct a bug in the alignment procedure leading to negative scores.
+- In `obimultiplex` correct a bug leading to a miss-read of the ngsfilter file when tags where written in
+  lower case.  
 
 ### New feature
 
diff --git a/pkg/obiformats/ngsfilter_read.go b/pkg/obiformats/ngsfilter_read.go
index 3cd0dd0..069c8fb 100644
--- a/pkg/obiformats/ngsfilter_read.go
+++ b/pkg/obiformats/ngsfilter_read.go
@@ -8,6 +8,7 @@ import (
 
 	"git.metabarcoding.org/lecasofts/go/obitools/pkg/obingslibrary"
 	"git.metabarcoding.org/lecasofts/go/obitools/pkg/obiseq"
+	log "github.com/sirupsen/logrus"
 )
 
 func _readLines(reader io.Reader) []string {
@@ -38,10 +39,12 @@ func _parseMainNGSFilterTags(text string) obingslibrary.TagPair {
 
 	tags := strings.Split(text, ":")
 
+	log.Infof("text: %s, Tags: %v", text, tags)
+
 	if len(tags) == 1 {
 		return obingslibrary.TagPair{
-			Forward: tags[0],
-			Reverse: tags[0],
+			Forward: strings.ToLower(tags[0]),
+			Reverse: strings.ToLower(tags[0]),
 		}
 	}