--- a/client.mk
+++ b/client.mk
@@ -115,16 +115,18 @@ endef
 # As $(shell) doesn't preserve newlines, use sed to replace them with an
 # unlikely sequence (||), which is then replaced back to newlines by make
 # before evaluation. $(shell) replacing newlines with spaces, || is always
 # followed by a space (since sed doesn't remove newlines), except on the
 # last line, so replace both '|| ' and '||'.
 MOZCONFIG_CONTENT := $(subst ||,$(CR),$(subst || ,$(CR),$(shell _PYMAKE=$(.PYMAKE) $(TOPSRCDIR)/$(MOZCONFIG_LOADER) $(TOPSRCDIR) | sed 's/$$/||/')))
 $(eval $(MOZCONFIG_CONTENT))
 
+export FOUND_MOZCONFIG
+
 # As '||' was used as a newline separator, it means it's not occurring in
 # lines themselves. It can thus safely be used to replaces normal spaces,
 # to then replace newlines with normal spaces. This allows to get a list
 # of mozconfig output lines.
 MOZCONFIG_OUT_LINES := $(subst $(CR), ,$(subst $(NULL) $(NULL),||,$(MOZCONFIG_CONTENT)))
 # Filter-out comments from those lines.
 START_COMMENT = \#
 MOZCONFIG_OUT_FILTERED := $(filter-out $(START_COMMENT)%,$(MOZCONFIG_OUT_LINES))