diff --git a/src/nf_modules/star/main_2.7.8a.nf b/src/nf_modules/star/main_2.7.8a.nf
index b544b2f91bce7ccfc5a6270c768835a12b8c84e1..e7be9f7edb1b5673422089dc1c936368a2cc187e 100644
--- a/src/nf_modules/star/main_2.7.8a.nf
+++ b/src/nf_modules/star/main_2.7.8a.nf
@@ -211,7 +211,7 @@ if (reads_id instanceof List){
 if (reads.size() == 2)
 """
 STAR --runThreadN ${task.cpus} \
---genomeDir $index \
+--genomeDir ${index} \
 --readFilesCommand zcat \
 --readFilesIn ${reads[0]} ${reads[1]} \
 --outFileNamePrefix ${reads_id}. \
@@ -224,7 +224,7 @@ mv ${reads_id}.Aligned.sortedByCoord.out.bam ${reads_id}.bam
 else
 """
 STAR --runThreadN ${task.cpus} \
---genomeDir $index \
+--genomeDir ${index} \
 --readFilesCommand zcat \
 --readFilesIn ${reads} \
 --outFileNamePrefix ${reads_id}. \