diff --git a/macs2.wdl b/macs2.wdl
index 81afcd1b6333ea4d22a94fa7fd038af1cbbc0580..2f8d97e9a07eedaa9c795cc39007a3533d9b2439 100644
--- a/macs2.wdl
+++ b/macs2.wdl
@@ -14,7 +14,7 @@ task PeakCalling {
         --treatment ${sep = ' ' bamFiles} \
         --outdir ${outDir} \
         --name ${sampleName} \
-        ${default=false true='--nomodel', false='' nomodel}
+        ${true='--nomodel' false='' default=false nomodel}
     }
 
     output {