diff --git a/modules/nf-core/deacon/index/main.nf b/modules/nf-core/deacon/index/main.nf
index 5c049c1c939c..eaa144f5780f 100644
--- a/modules/nf-core/deacon/index/main.nf
+++ b/modules/nf-core/deacon/index/main.nf
@@ -26,7 +26,7 @@ process DEACON_INDEX {
         build \\
         --threads ${task.cpus} \\
         $args \\
-        $fasta > ${prefix}.idx
+        $fasta > ${fasta.baseName}.idx
     """
 
     stub:
diff --git a/modules/nf-core/deacon/index/tests/main.nf.test.snap b/modules/nf-core/deacon/index/tests/main.nf.test.snap
index 46fd18904791..0ef58d4337a1 100644
--- a/modules/nf-core/deacon/index/tests/main.nf.test.snap
+++ b/modules/nf-core/deacon/index/tests/main.nf.test.snap
@@ -7,7 +7,7 @@
                         {
                             "id": "test"
                         },
-                        "test.idx:md5,84e4985c91800686db9c9dca28fabd1a"
+                        "genome.idx:md5,84e4985c91800686db9c9dca28fabd1a"
                     ]
                 ],
                 "versions_deacon": [
@@ -19,7 +19,7 @@
                 ]
             }
         ],
-        "timestamp": "2026-06-25T08:36:03.824580444",
+        "timestamp": "2026-07-03T15:17:04.349357336",
         "meta": {
             "nf-test": "0.9.5",
             "nextflow": "26.04.3"
@@ -59,7 +59,7 @@
                         {
                             "id": "test"
                         },
-                        "test.idx:md5,84e4985c91800686db9c9dca28fabd1a"
+                        "genome.fasta.idx:md5,84e4985c91800686db9c9dca28fabd1a"
                     ]
                 ],
                 "versions_deacon": [
@@ -71,7 +71,7 @@
                 ]
             }
         ],
-        "timestamp": "2026-06-25T08:36:10.326633427",
+        "timestamp": "2026-07-03T15:17:09.942121648",
         "meta": {
             "nf-test": "0.9.5",
             "nextflow": "26.04.3"