diff --git a/collect-columns.wdl b/collect-columns.wdl
index 68c9dcc884563d41e6322440e2f0743368c65ef7..9e18f51e8333fe5beab7bdbf40a1a35244db7364 100644
--- a/collect-columns.wdl
+++ b/collect-columns.wdl
@@ -13,7 +13,7 @@ task CollectColumns {
         File? referenceGtf
         String? featureAttribute
 
-        String dockerTag = "0.2.0--py_1"
+        String dockerImage = "quay.io/biocontainers/collect-columns:0.2.0--py_1"
     }
 
     command {
@@ -36,6 +36,6 @@ task CollectColumns {
 
     runtime {
         memory: 4 + ceil(0.5* length(inputTables))
-        docker: "quay.io/biocontainers/collect-columns:" + dockerTag
+        docker: dockerImage
     }
 }
\ No newline at end of file
diff --git a/htseq.wdl b/htseq.wdl
index a687a8a6242b4ec0a8b1dd2b3b46b5a2c49d3923..ed13167cc800627a8370634d667f96022c3bfe5a 100644
--- a/htseq.wdl
+++ b/htseq.wdl
@@ -11,7 +11,7 @@ task HTSeqCount {
         String stranded = "no"
 
         Int memory = 40
-        String dockerTag = "0.9.1--py36h7eb728f_2"
+        String dockerImage = "quay.io/biocontainers/htseq:0.9.1--py36h7eb728f_2"
     }
 
     command {
@@ -32,6 +32,6 @@ task HTSeqCount {
 
     runtime {
         memory: memory
-        docker: "quay.io/biocontainers/htseq:" + dockerTag
+        docker: dockerImage
     }
 }
\ No newline at end of file