diff --git a/tests/docker/Makefile.include b/tests/docker/Makefile.include
index f1a398e9fa..de87341528 100644
--- a/tests/docker/Makefile.include
+++ b/tests/docker/Makefile.include
@@ -109,7 +109,7 @@ docker:
 	@echo '    DEBUG=1              Stop and drop to shell in the created container'
 	@echo '                         before running the command.'
 	@echo '    NETWORK=1            Enable virtual network interface with default backend.'
-	@echo '    NETWORK=$BACKEND     Enable virtual network interface with $BACKEND.'
+	@echo '    NETWORK=$$BACKEND     Enable virtual network interface with $$BACKEND.'
 	@echo '    NOUSER               Define to disable adding current user to containers passwd.'
 	@echo '    NOCACHE=1            Ignore cache when build images.'
 	@echo '    EXECUTABLE=<path>    Include executable in image.'