diff --git a/.gitignore b/.gitignore
index 23a558a..22ce0e1 100644
--- a/.gitignore
+++ b/.gitignore
@@ -7,4 +7,8 @@ build/
 .devenv
 result
 target/
+
+# justfile testing
 *.fastq.gz
+*.fa
+dragmap/
diff --git a/justfile b/justfile
index 2b43353..eb4257f 100644
--- a/justfile
+++ b/justfile
@@ -1,8 +1,16 @@
 dragen  := "./result/bin/dragen-os"
 
-test_segfault: test_data
-    {{dragen}} -r narfmap --RGSM null --num-threads 2 -1 SRX882903_T2.fastq.gz
+test_segfault: # test_data build_reference
+    {{dragen}} -r dragmap --RGSM test --num-threads 2 -1 SRX882903_T2.fastq.gz > output.log
+
+build_reference: test_data
+    # mkdir dragmap
+    {{dragen}} \
+        --build-hash-table true \
+        --ht-reference GRCh38_chr21.fa \
+        --output-directory dragmap \
+        --ht-num-threads 2
 
 test_data:
     wget https://raw.githubusercontent.com/nf-core/test-datasets/nascent/testdata/SRX882903_T2.fastq.gz
-
+    wget https://raw.githubusercontent.com/nf-core/test-datasets/nascent/reference/GRCh38_chr21.fa