diff --git a/centos7/Makefile b/centos7/Makefile
index 6f2bf5a2..436a1e31 100644
--- a/centos7/Makefile
+++ b/centos7/Makefile
@@ -4,8 +4,18 @@ include ../scripts/check.mk
 
 PACKER ?= packer
 PACKER_LOG ?= 0
-KS_MIRROR ?= http://mirrorlist.centos.org
-export PACKER_LOG KS_PROXY KS_MIRROR
+
+ifneq (${KS_MIRROR},)
+KS_OS_REPOS := --url="${KS_MIRROR}/os/x86_64"
+KS_UPDATES_REPOS := --baseurl="${KS_MIRROR}/updates/x86_64"
+KS_EXTRA_REPOS := --baseurl="${KS_MIRROR}/extras/x86_64"
+else
+KS_OS_REPOS := --mirrorlist="http://mirrorlist.centos.org/?release=7&arch=x86_64&repo=os"
+KS_UPDATES_REPOS := --mirrorlist="http://mirrorlist.centos.org/?release=7&arch=x86_64&repo=updates"
+KS_EXTRA_REPOS := --mirrorlist="http://mirrorlist.centos.org/?release=7&arch=x86_64&repo=extras"
+endif
+
+export PACKER_LOG KS_PROXY KS_OS_REPOS KS_UPDATES_REPOS KS_EXTRA_REPOS
 
 .PHONY: all clean check-deps
 
@@ -17,7 +27,7 @@ centos7.tar.gz: clean check-deps http/centos7.ks
 	${PACKER} init centos7.pkr.hcl && ${PACKER} build centos7.pkr.hcl
 
 http/centos7.ks: http/centos7.ks.in
-	envsubst '$${KS_PROXY} $${KS_MIRROR}' < $< | tee $@
+	envsubst '$${KS_PROXY} $${KS_OS_REPOS} $${KS_UPDATES_REPOS} $${KS_EXTRA_REPOS}' < $< | tee $@
 
 clean:
 	${RM} -rf output-centos7 centos7.tar.gz http/centos7.ks
diff --git a/centos7/http/centos7.ks.in b/centos7/http/centos7.ks.in
index 92ff3d58..8c618790 100644
--- a/centos7/http/centos7.ks.in
+++ b/centos7/http/centos7.ks.in
@@ -1,4 +1,4 @@
-url --mirrorlist="${KS_MIRROR}/?release=7&arch=x86_64&repo=os" ${KS_PROXY}
+url ${KS_OS_REPOS} ${KS_PROXY}
 poweroff
 firewall --enabled --service=ssh
 firstboot --disable
@@ -12,8 +12,8 @@ timezone UTC --isUtc
 bootloader --location=mbr --driveorder="vda" --timeout=1
 rootpw --plaintext password
 
-repo --name="Updates" --mirrorlist="${KS_MIRROR}/?release=7&arch=x86_64&repo=updates" ${KS_PROXY}
-repo --name="Extras" --mirrorlist="${KS_MIRROR}/?release=7&arch=x86_64&repo=extras" ${KS_PROXY}
+repo --name="Updates" ${KS_UPDATES_REPOS} ${KS_PROXY}
+repo --name="Extras" ${KS_EXTRA_REPOS} ${KS_PROXY}
 
 zerombr
 clearpart --all --initlabel