diff --git a/gatk.wdl b/gatk.wdl
index 0d36e440981fa853df575b20a2258259bde06d86..939513db6a92d2f4b4fda5fdf22c26a079be68f0 100644
--- a/gatk.wdl
+++ b/gatk.wdl
@@ -734,7 +734,7 @@ task GatherBqsrReports {
     command {
         set -e
         mkdir -p "$(dirname ~{outputReportPath})"
-        gatk --java-options '-Xmx~{javaXmxMb} -XX:ParallelGCThreads=1' \
+        gatk --java-options '-Xmx~{javaXmxMb}M -XX:ParallelGCThreads=1' \
         GatherBQSRReports \
         -I ~{sep=' -I ' inputBQSRreports} \
         -O ~{outputReportPath}