--- a/build/Makefile.in
+++ b/build/Makefile.in
@@ -131,16 +131,17 @@ check::
 	@if ! file -b ./unify-test-universal | head -n1 | grep -q "^Mach-O universal binary"; then \
           echo "TEST-UNEXPECTED-FAIL | build/ | unify failed to produce a universal binary!"; \
           false; \
         else \
           echo "TEST-PASS | build/ | unify produced a universal binary!"; \
         fi
 # try building an x86-64 binary. if that succeeds, try unifying it
 # with an i386 binary
+	rm -f unify-test-x86_64 unify-test-universal-64
 	-$(HOST_CC) -arch x86_64 $(srcdir)/unify-test.c -o unify-test-x86_64
 	@if test -f ./unify-test-x86_64; then \
           if ! $(srcdir)/macosx/universal/unify ./unify-test-x86_64 ./unify-test-i386 \
             ./unify-test-universal-64; then \
             echo "TEST-UNEXPECTED-FAIL | build/ | unify failed to produce a universal binary with a 64-bit input!"; \
             false; \
           fi; \
           if test ! -f ./unify-test-universal-64; then \