diff --git a/alpine/Dockerfile.bios b/alpine/Dockerfile.bios
index 5ab3087cb..c2cf713de 100644
--- a/alpine/Dockerfile.bios
+++ b/alpine/Dockerfile.bios
@@ -9,7 +9,7 @@ RUN mkdir -p /tmp/iso/isolinux && \
     cp /usr/share/syslinux/isolinux.bin /tmp/iso/isolinux && \
     cp /usr/share/syslinux/ldlinux.c32 /tmp/iso/isolinux
 
-COPY initrd.img /tmp/iso
+COPY initrd.img.gz /tmp/iso
 COPY kernel/x86_64/vmlinuz64 /tmp/iso
 COPY isolinux.cfg /tmp/iso/isolinux
 
diff --git a/alpine/Dockerfile.efi b/alpine/Dockerfile.efi
index b455880d6..8768f515f 100644
--- a/alpine/Dockerfile.efi
+++ b/alpine/Dockerfile.efi
@@ -1,14 +1,10 @@
 # Create a EFI Bootable ISO
 FROM alpine:3.4
 
-ENV ARCH=x86_64
-
 RUN apk add --no-cache binutils mtools xorriso gummiboot
 
-RUN mkdir -p /tmp/efi
-
-COPY initrd.img.gz /tmp/efi
-COPY kernel/$ARCH/vmlinuz64 /tmp/efi
+COPY initrd.img.gz /tmp/efi/
+COPY kernel/x86_64/vmlinuz64 /tmp/efi/
 
 # Create a EFI boot file with kernel and initrd. From:
 # https://github.com/haraldh/mkrescue-uefi/blob/master/mkrescue-uefi.sh
diff --git a/alpine/Makefile b/alpine/Makefile
index 41cce6627..d848c9136 100644
--- a/alpine/Makefile
+++ b/alpine/Makefile
@@ -36,13 +36,13 @@ initrd.img: Dockerfile mkinitrd.sh init $(ETCFILES) common
 initrd.img.gz: initrd.img
 	cat initrd.img | gzip -9 > initrd.img.gz
 
-mobylinux-efi.iso: initrd.img.gz Dockerfile.efi
-	docker build -t moby-efi:build -f Dockerfile.efi .
+mobylinux-efi.iso: Dockerfile.efi initrd.img.gz kernel/x86_64/vmlinuz64
+	tar cf - $^ | docker build -t moby-efi:build -f Dockerfile.efi -
 	docker run --net=none --rm --cap-add sys_admin moby-efi:build cat /tmp/efi/mobylinux.efi > mobylinux.efi
 	docker run --net=none --rm --cap-add sys_admin moby-efi:build cat /tmp/efi/mobylinux-efi.iso > $@
 
-mobylinux-bios.iso: initrd.img Dockerfile.bios isolinux.cfg
-	docker build -t moby-bios:build -f Dockerfile.bios .
+mobylinux-bios.iso: Dockerfile.bios initrd.img.gz kernel/x86_64/vmlinuz64 isolinux.cfg
+	tar cf - $^ | docker build -t moby-bios:build -f Dockerfile.bios -
 	docker run --net=none --rm moby-bios:build cat /tmp/mobylinux-bios.iso > $@
 
 common: initrd.img
diff --git a/alpine/isolinux.cfg b/alpine/isolinux.cfg
index 660d27c6c..9c700b21a 100644
--- a/alpine/isolinux.cfg
+++ b/alpine/isolinux.cfg
@@ -1,5 +1,5 @@
 DEFAULT linux
 LABEL linux
     KERNEL /vmlinuz64
-    INITRD /initrd.img
+    INITRD /initrd.img.gz
     APPEND earlyprintk=serial console=ttyS0 console=tty1