diff --git a/dist/testbed-support/Makefile.iotlab b/dist/testbed-support/Makefile.iotlab
index 8e121a6aa52b5b21c563e319a0f9a50384861ca9..bd2e902f98ec50343f6a6880fd1b13ab4ea9ab38 100644
--- a/dist/testbed-support/Makefile.iotlab
+++ b/dist/testbed-support/Makefile.iotlab
@@ -81,7 +81,4 @@ iotlab-term: iotlab-check-exp
 	RIOT_LOG-$(IOTLAB_EXP_NAME)-$(IOTLAB_EXP_ID), \
 	serial_aggregator -i $(IOTLAB_EXP_ID) $(NODES_PARAM_BASE))'"
 
-iotlab-check-exp:
-ifndef IOTLAB_SITE
-	$(eval IOTLAB_SITE := $(shell experiment-cli get -ri -i $(IOTLAB_EXP_ID) | sed -n 4p | cut -d\" -f2))
-endif
+iotlab-check-exp: IOTLAB_SITE ?= $(shell experiment-cli get -ri -i $(IOTLAB_EXP_ID) | sed -n 4p | cut -d\" -f2)