diff --git a/make/dirs.mk b/make/dirs.mk
index 358f3534..b86b820b 100644
--- a/make/dirs.mk
+++ b/make/dirs.mk
@@ -49,7 +49,9 @@ $(foreach t,$(filter-out all install clean distclean,$(ALLOWED_SUBDIR_TARGETS)),
 
 %/dirs-all.done:
 	@echo $@ needs to be rebuilt
+ifneq ($(DONT_CHECK_PREREQ_PROJECTS),true)
 	exit 1
+endif
 
 # explicit duplication of pattern-rule is needed, otherwise .PHONY: dirs-all.done won't match
 dirs-all.done: