diff --git a/make/projects-dir.mk b/make/projects-dir.mk
index 843c629a..2b84d96c 100644
--- a/make/projects-dir.mk
+++ b/make/projects-dir.mk
@@ -89,7 +89,11 @@ else
 endif
 
 ifeq ($(filter pkg-%,$(MAKECMDGOALS)),)
-  export JW_BUILD_SSH_EXTRA_OPTS += -o StrictHostKeyChecking=no -o ControlMaster=auto -o ControlPath=/tmp/%r@jw-build:%h:%p -o ControlPersist=3m -l $(JANWARE_USER)
+  JW_BUILD_SSH_EXTRA_OPTS += -o StrictHostKeyChecking=no -o ControlMaster=auto -o ControlPath=/tmp/%r@jw-build:%h:%p -o ControlPersist=3m
+  ifneq ($(JANWARE_USER),)
+    JW_BUILD_SSH_EXTRA_OPTS += -l $(JANWARE_USER)
+  endif
+  export JW_BUILD_SSH_EXTRA_OPTS
 endif
 
 ifneq ($(EXCLUDE_FROM_BUILD),)