diff --git a/crypto/ts/Makefile b/crypto/ts/Makefile
index ad29b67bd..c18234555 100644
--- a/crypto/ts/Makefile
+++ b/crypto/ts/Makefile
@@ -60,7 +60,8 @@ links:
 	@$(PERL) $(TOP)/util/mklink.pl ../../apps $(APPS)
 
 install:
-	@for i in $(EXHEADER) ; \
+	@[ -n "$(INSTALLTOP)" ] # should be set by top Makefile...
+	@headerlist="$(EXHEADER)"; for i in $$headerlist ; \
 	do  \
 	(cp $$i $(INSTALL_PREFIX)$(INSTALLTOP)/include/openssl/$$i; \
 	chmod 644 $(INSTALL_PREFIX)$(INSTALLTOP)/include/openssl/$$i ); \