diff --git a/bio/picard/mergevcfs/test/Snakefile b/bio/picard/mergevcfs/test/Snakefile
index 6ee584cdad..c04291dd5a 100644
--- a/bio/picard/mergevcfs/test/Snakefile
+++ b/bio/picard/mergevcfs/test/Snakefile
@@ -1,6 +1,6 @@
 rule merge_vcfs:
     input:
-        ["snvs.chr1.vcf", "snvs.chr2.vcf"]
+        vcfs=["snvs.chr1.vcf", "snvs.chr2.vcf"]
     output:
         "snvs.vcf"
     log:
diff --git a/bio/picard/mergevcfs/wrapper.py b/bio/picard/mergevcfs/wrapper.py
index 59b69c83d5..4443dd53f5 100644
--- a/bio/picard/mergevcfs/wrapper.py
+++ b/bio/picard/mergevcfs/wrapper.py
@@ -9,7 +9,7 @@
 from snakemake.shell import shell
 
 
-inputs = " ".join("INPUT={}".format(f) for f in snakemake.input)
+inputs = " ".join("INPUT={}".format(f) for f in snakemake.input.vcfs)
 log = snakemake.log_fmt_shell(stdout=False, stderr=True)
 extra = snakemake.params.get("extra", "")