diff --git a/src/install.sh b/src/install.sh
index 345b8945..3a1fcbbd 100644
--- a/src/install.sh
+++ b/src/install.sh
@@ -279,9 +279,15 @@ startInstall() {
   skipInstall "$BOOT" "$previousBase" && return 1
 
   if [ -z "$previousBase" ] && hasData; then
-    if ! backupPrevious ""; then
-      warn "the backup was incomplete, continuing with installation..."
+
+    if enabled "$SHUTDOWN" && [ ! -f "$STORAGE/windows.boot" ]; then
+      discardPrevious "" || exit 50
+    else
+      if ! backupPrevious ""; then
+        warn "the backup was incomplete, continuing with installation..."
+      fi
     fi
+
   fi
 
   if ! makeDir "$TMP"; then
@@ -374,7 +380,7 @@ skipUnattended() {
 
   # Preserve custom media in place. Downloaded or reused media must be moved
   # back to persistent storage before the manual fallback is started.
-  useOriginalImage "$iso"
+  useOriginalImage "$iso" || return 1
 
   finishInstall "$BOOT" "$aborted" "$boot" && return 0
   return 1
@@ -467,6 +473,11 @@ skipInstall() {
         fi
       fi
 
+      if enabled "$SHUTDOWN" && [ ! -f "$boot" ]; then
+        discardPrevious "$STORAGE/$previousBase" || exit 50
+        return 1
+      fi
+
       info "Detected that $method, a backup of your previous installation will be saved..."
 
       if ! backupPrevious "$STORAGE/$previousBase"; then
@@ -624,7 +635,10 @@ removeImage() {
 
   [ -n "$CUSTOM" ] && return 0
 
-  rm -f -- "$iso" 2>/dev/null || warn "failed to remove image \"$iso\"!"
+  if ! rm -f -- "$iso" 2>/dev/null; then
+    warn "failed to remove image \"$iso\"!"
+    return 1
+  fi
 
   return 0
 }
@@ -1264,6 +1278,27 @@ reserveSambaPorts() {
   return 0
 }
 
+discardPrevious() {
+
+  local iso="$1"
+
+  if [ -n "$iso" ] && [ -f "$iso" ]; then
+    if ! rm -f -- "$iso"; then
+      error "Failed to remove ISO file \"$iso\" !"
+      return 1
+    fi
+  fi
+
+  if ! find "$STORAGE" -maxdepth 1 -type f \
+    \( -iname 'data.*' -or -iname 'windows.*' -or -iname '*.rom' -or -iname '*.vars' \) \
+    -not -iname '*.iso' -delete; then
+    error "Failed to remove unfinished installation files from \"$STORAGE\" !"
+    return 1
+  fi
+
+  return 0
+}
+
 backupPrevious () {
 
   local iso="$1"
diff --git a/src/mido.sh b/src/mido.sh
index 19e83e31..f7940167 100644
--- a/src/mido.sh
+++ b/src/mido.sh
@@ -1379,10 +1379,7 @@ fallbackEnglish() {
   # still locate the same image, but use English installation media.
   LANGUAGE="en"
 
-  if ! rm -f -- "$iso"; then
-    error "Failed to remove ISO file \"$iso\" !"
-    return 1
-  fi
+  removeImage "$iso" || return 1
 
   downloadImage "$iso" "$version" "$LANGUAGE"
 }