diff --git a/client.mk b/client.mk
index 13f682a7c71..9f480fef116 100644
--- a/client.mk
+++ b/client.mk
@@ -777,7 +777,7 @@ else
 # this point when building multiple projects.  Only MOZ_OBJDIR is available.
 	set -e; \
 	for mkfile in $(MOZ_PREFLIGHT_ALL); do \
-	  $(MAKE) -f $$mkfile preflight_all TOPSRCDIR=$(TOPSRCDIR) MOZ_OBJDIR=$(MOZ_OBJDIR); \
+	  $(MAKE) -f $$mkfile preflight_all TOPSRCDIR=$(TOPSRCDIR) MOZ_OBJDIR=$(MOZ_OBJDIR) MOZ_BUILD_PROJECTS="$(MOZ_BUILD_PROJECTS)"; \
 	done
 endif
 endif
@@ -937,7 +937,7 @@ else
 # this point when building multiple projects.  Only MOZ_OBJDIR is available.
 	set -e; \
 	for mkfile in $(MOZ_POSTFLIGHT_ALL); do \
-	  $(MAKE) -f $$mkfile postflight_all TOPSRCDIR=$(TOPSRCDIR) MOZ_OBJDIR=$(MOZ_OBJDIR); \
+	  $(MAKE) -f $$mkfile postflight_all TOPSRCDIR=$(TOPSRCDIR) MOZ_OBJDIR=$(MOZ_OBJDIR) MOZ_BUILD_PROJECTS="$(MOZ_BUILD_PROJECTS)"; \
 	done
 endif
 endif