diff --git a/certs/Makefile b/certs/Makefile
index a702b70f3cb9c9d9a9280c9677deee5f9cc84857..aba9e782f940933dbf876f771b6cc96756b72819 100644
--- a/certs/Makefile
+++ b/certs/Makefile
@@ -60,9 +60,8 @@ keytype-$(CONFIG_MODULE_SIG_KEY_TYPE_ECDSA) := -newkey ec -pkeyopt ec_paramgen_c
 
 quiet_cmd_gen_key = GENKEY  $@
       cmd_gen_key = openssl req -new -nodes -utf8 -$(CONFIG_MODULE_SIG_HASH) -days 36500 \
-		-batch -x509 -config $(obj)/x509.genkey \
-		-outform PEM -out $(obj)/signing_key.pem \
-		-keyout $(obj)/signing_key.pem $(keytype-y) 2>&1
+		-batch -x509 -config $< \
+		-outform PEM -out $@ -keyout $@ $(keytype-y) 2>&1
 
 $(obj)/signing_key.pem: $(obj)/x509.genkey FORCE
 	$(call if_changed,gen_key)