diff --git a/docs/usage.md b/docs/usage.md
index 180e8018..62b5aae1 100644
--- a/docs/usage.md
+++ b/docs/usage.md
@@ -139,8 +139,9 @@ test_scARC,path/test_scARC_gex_S1_L002_R1_001.fastq.gz,path/test_scARC_gex_S1_L0
 
 #### Config file and index
 
-Cellranger-arc needs a reference index directory that you can provide with `--cellranger_index`. Be aware, you can use
-for cellranger-arc the same index you use for cellranger ([see](https://kb.10xgenomics.com/hc/en-us/articles/4408281606797-Are-the-references-interchangeable-between-pipelines)).
+Cellranger-arc needs a reference index directory that you can provide with `--cellranger_index`.
+Besure to provide the base path of the index (e.g., `--cellranger_index /PATH/TO/10X_REF/refdata-gex-GRCh38-2024-A/`).
+Be aware, you can use for cellranger-arc the same index you use for cellranger ([see](https://kb.10xgenomics.com/hc/en-us/articles/4408281606797-Are-the-references-interchangeable-between-pipelines)).
 Yet, a cellranger-arc index might include additional data (e.g., TF binding motifs). Therefore, please first check if
 you have to create a new cellranger-arc index ([see here](https://support.10xgenomics.com/single-cell-multiome-atac-gex/software/pipelines/latest/advanced/references) for
 more information)
diff --git a/nextflow_schema.json b/nextflow_schema.json
index 4298beb0..dd945d19 100644
--- a/nextflow_schema.json
+++ b/nextflow_schema.json
@@ -278,7 +278,7 @@
             "properties": {
                 "cellranger_index": {
                     "type": "string",
-                    "description": "Specify a pre-calculated cellranger index. Readily prepared indexes can be obtained from the 10x Genomics website. ",
+                    "description": "Specify a pre-calculated cellranger index. Readily prepared indexes can be obtained from the 10x Genomics website. Provide the base directory of the index (e.g., '/PATH/TO/10X_REF/refdata-gex-GRCh38-2024-A/')",
                     "format": "path",
                     "exists": true
                 },