diff --git a/common.mk b/common.mk
index 817f6ec061..b00a6df667 100644
--- a/common.mk
+++ b/common.mk
@@ -1351,9 +1351,10 @@ no-test-bundler:
 
 PARALLELRSPECOPTS = --runtime-log $(srcdir)/tmp/parallel_runtime_rspec.log
 test-bundler-parallel: $(TEST_RUNNABLE)-test-bundler-parallel
+PARALLEL_TESTS_EXECUTABLE = $(XRUBY)
 yes-test-bundler-parallel: yes-test-bundler-prepare
 	$(XRUBY) -C $(srcdir) -Ispec/bundler .bundle/bin/parallel_rspec \
-		-o "--require $(srcdir)/spec/bundler/spec_helper \
+		-o "--require $(srcdir)/spec/bundler/spec_helper" \
 		$(PARALLELRSPECOPTS) spec/bundler/$(BUNDLER_SPECS)
 no-test-bundler-parallel: