diff --git a/macs2.wdl b/macs2.wdl
index dd3226ac124f9fd6bfd443581308ebf41e6322a8..f0420c11667ace6a3fc58d57ba4e731debee196f 100644
--- a/macs2.wdl
+++ b/macs2.wdl
@@ -14,7 +14,7 @@ task PeakCalling {
         --treatment ${sep = ' ' bamFiles} \
         --outdir ${outDir} + "/macs2/" \
         --name ${sampleName} \
-        ${default=false true='--nomodel' false='' nomodel}
+        ${true='--nomodel' false='' nomodel}
     }
 
     output {