diff --git a/deploy.fish b/deploy.fish
index 463bf91..8fb8ee3 100644
--- a/deploy.fish
+++ b/deploy.fish
@@ -12,6 +12,7 @@ begin
     set -l setupLabel "winiso-valhalla"
     set -l buildDir "$(status dirname)/build"
     set -l cacheDir ~/.cache/winiso-valhalla
+    set -l isoFile "$buildDir/winiso-valhalla.iso"
     set -l winpe "$cacheDir/winpe.iso"
     set -l winPath "/media/win"
     set -l winpePath "/media/winpe"
@@ -20,6 +21,8 @@ begin
     set -l dataPath "/media/data"
     set -l winpeOverlay (mktemp -d)
     set -l winOverlay (mktemp -d)
+    set -l upperDir (mktemp -d)
+    set -l workDir (mktemp -d)
     set -l editionField "Edition ID"
     set -l wimFile "sources/install.wim"
 
@@ -113,67 +116,82 @@ begin
         end
     end
 
-    sudo mount --mkdir -t overlay overlay -o lowerdir="$winOverlay":"$winPath" "$valhallaPath"
+    sudo mount --mkdir -t overlay overlay -o lowerdir="$winOverlay":"$winpePath":"$winPath",upperdir="$upperDir",workdir="$workDir" "$valhallaPath"
 
-    if [ ! -b "$WIN_DISK" ]
-        chooseDisk WIN_DISK
-    end
-
-    sudo shred -vfzn 0 -s 512 "$WIN_DISK"
-
-    begin
-        printf %s\n \
-            o \
-            n \
-            "" \
-            "" \
-            "" \
-            +2G \
-            y \
-            t \
-            c \
-            a \
-            "" \
-            \
-            n \
-            "" \
-            "" \
-            "" \
-            "" \
-            y \
-            t \
-            "" \
-            7 \
-            \
-            w
-    end | sudo fdisk "$WIN_DISK"
-
-    begin
-        set -l disks
-
-        while true
-            set disks (string split -n " " (bash -c "echo $WIN_DISK*"))
-            [ (count $disks) -ge 3 ] && break
+    if [ -z "$_flag_usb" ]
+        mkisofs \
+            -V "$setupLabel" \
+            -no-emul-boot \
+            -b "efi/microsoft/boot/efisys.bin" \
+            -iso-level 4 \
+            -udf \
+            -joliet \
+            -disable-deep-relocation \
+            -omit-version-number \
+            -relaxed-filenames \
+            -output "$isoFile" \
+            "$valhallaPath"
+    else
+        if [ ! -b "$WIN_DISK" ]
+            chooseDisk WIN_DISK
         end
 
-        set -l bootDisk "$disks[2]"
-        set -l dataDisk "$disks[3]"
-        sudo mkfs.fat -F 32 -n "BOOT" "$bootDisk"
-        sudo mkfs.ntfs -fFL "$setupLabel" "$dataDisk"
-        sudo mount --mkdir "$bootDisk" "$bootPath"
-        sudo mount --mkdir "$dataDisk" "$dataPath"
-        sudo cp -r "$winpePath"/* "$bootPath"
+        sudo shred -vfzn 0 -s 512 "$WIN_DISK"
 
-        sudo cp -r "$valhallaPath"/* "$dataPath"
-        sudo cp -r "$valhallaPath/efi" "$bootPath"
+        begin
+            printf %s\n \
+                o \
+                n \
+                "" \
+                "" \
+                "" \
+                +2G \
+                y \
+                t \
+                c \
+                a \
+                "" \
+                \
+                n \
+                "" \
+                "" \
+                "" \
+                "" \
+                y \
+                t \
+                "" \
+                7 \
+                \
+                w
+        end | sudo fdisk "$WIN_DISK"
 
-        for path in "$valhallaPath" \
-                    "$winPath" \
-                    "$winpePath" \
-                    "$bootPath" \
-                    "$dataPath"
-            sudo umount -vf "$path"
-            sudo rm -rf "$path"
+        begin
+            set -l disks
+
+            while true
+                set disks (string split -n " " (bash -c "echo $WIN_DISK*"))
+                [ (count $disks) -ge 3 ] && break
+            end
+
+            set -l bootDisk "$disks[2]"
+            set -l dataDisk "$disks[3]"
+            sudo mkfs.fat -F 32 -n "BOOT" "$bootDisk"
+            sudo mkfs.ntfs -fFL "$setupLabel" "$dataDisk"
+            sudo mount --mkdir "$bootDisk" "$bootPath"
+            sudo mount --mkdir "$dataDisk" "$dataPath"
+            sudo cp -r "$winpePath"/* "$bootPath"
+
+            sudo cp -r "$valhallaPath"/* "$dataPath"
+            sudo cp -r "$valhallaPath/efi" "$bootPath"
+
+            for path in "$valhallaPath" \
+                        "$winPath" \
+                        "$winpePath" \
+                        "$bootPath" \
+                        "$dataPath"
+                sudo umount -vf "$path"
+                sudo rm -rf "$path"
+            end
         end
     end
 end