diff --git a/examples/energest-demo/Makefile.contiki-energest-demo b/examples/energest-demo/Makefile.contiki-energest-demo
index eb44e7af2..d31cf089f 100644
--- a/examples/energest-demo/Makefile.contiki-energest-demo
+++ b/examples/energest-demo/Makefile.contiki-energest-demo
@@ -10,4 +10,4 @@ upload-node-%:
 upload-sink: upload-node-41
 
 rundemo:
-	java -jar energest.jar /dev/com$(CMOTES)
+	java -jar energest.jar /dev/com${firstword $(CMOTES)}