diff --git a/workflow/snakefile b/workflow/snakefile
index 1ab1b08..a6e7360 100644
--- a/workflow/snakefile
+++ b/workflow/snakefile
@@ -112,10 +112,10 @@ rule sam_to_bam_format:
         sed 's/^[[:space:]]*//' > tmp_files/06_sam_to_bam_format/{wildcards.barcode}_abundance.tsv
         if [ ! -s tmp_files/06_sam_to_bam_format/{wildcards.barcode}_abundance.tsv ]; then
             echo '1 XXX' >> tmp_files/06_sam_to_bam_format/{wildcards.barcode}_abundance.tsv
-            grep -o '[^ ]\+$' tmp_files/06_sam_to_bam_format/{wildcards.barcode}_abundance.tsv > {output.ASV_list}
+            grep -Eo "[^ ]+$" tmp_files/06_sam_to_bam_format/{wildcards.barcode}_abundance.tsv > {output.ASV_list}
             echo 'XXX XXX;XXX;XXX;XXX;XXX;SANITY'> {output.taxonomy_file}
         else
-            grep -o '[^ ]\+$' tmp_files/06_sam_to_bam_format/{wildcards.barcode}_abundance.tsv > {output.ASV_list}
+            grep -Eo "[^ ]+$" tmp_files/06_sam_to_bam_format/{wildcards.barcode}_abundance.tsv > {output.ASV_list}
             grep -f {output.ASV_list} tmp_files/00_database_indexing/TAXONOMY_{DATABASE_NAME} > {output.taxonomy_file}
         fi
         """
@@ -227,4 +227,4 @@ rule phyloseq:
         """
         Rscript {NANOASV_PATH}/workflow/scripts/script.r {INPUT_DIR} {OUT} {R_CLEANING} {TREE} {METADATA} 2> /dev/null
         touch {output}
-        """
\ No newline at end of file
+        """