diff --git a/modules/gatk4/mergebamalignment/main.nf b/modules/gatk4/mergebamalignment/main.nf
index b0b9daa1..0e294454 100644
--- a/modules/gatk4/mergebamalignment/main.nf
+++ b/modules/gatk4/mergebamalignment/main.nf
@@ -8,8 +8,7 @@ process GATK4_MERGEBAMALIGNMENT {
         'quay.io/biocontainers/gatk4:4.2.4.1--hdfd78af_0' }"
 
     input:
-    tuple val(meta), path(aligned)
-    path  unmapped
+    tuple val(meta), path(aligned), path(unmapped)
     path  fasta
     path  dict
 
@@ -28,10 +27,10 @@ process GATK4_MERGEBAMALIGNMENT {
     }
     """
     gatk --java-options "-Xmx${avail_mem}g" MergeBamAlignment \\
-        ALIGNED=$aligned \\
-        UNMAPPED=$unmapped \\
-        R=$fasta \\
-        O=${prefix}.bam \\
+        -ALIGNED $aligned \\
+        -UNMAPPED $unmapped \\
+        -R $fasta \\
+        -O ${prefix}.bam \\
         $args
 
     cat <<-END_VERSIONS > versions.yml
diff --git a/tests/modules/gatk4/mergebamalignment/main.nf b/tests/modules/gatk4/mergebamalignment/main.nf
index 59bd833b..8a38c129 100644
--- a/tests/modules/gatk4/mergebamalignment/main.nf
+++ b/tests/modules/gatk4/mergebamalignment/main.nf
@@ -6,11 +6,11 @@ include { GATK4_MERGEBAMALIGNMENT } from '../../../../modules/gatk4/mergebamalig
 
 workflow test_gatk4_mergebamalignment {
     input    = [ [ id:'test' ], // meta map
-                 file(params.test_data['sarscov2']['illumina']['test_single_end_bam'], checkIfExists: true)
+                 file(params.test_data['sarscov2']['illumina']['test_single_end_bam'], checkIfExists: true),
+                 file(params.test_data['sarscov2']['illumina']['test_unaligned_bam'], checkIfExists: true)
                ]
-    unmapped = file(params.test_data['sarscov2']['illumina']['test_unaligned_bam'], checkIfExists: true)
     fasta    = file(params.test_data['sarscov2']['genome']['genome_fasta'], checkIfExists: true)
     dict     = file(params.test_data['sarscov2']['genome']['genome_dict'], checkIfExists: true)
 
-    GATK4_MERGEBAMALIGNMENT ( input, unmapped, fasta, dict )
+    GATK4_MERGEBAMALIGNMENT ( input, fasta, dict )
 }