diff --git a/script/add-grammar b/script/add-grammar
index d7469d31..0bc48454 100755
--- a/script/add-grammar
+++ b/script/add-grammar
@@ -43,13 +43,21 @@ def log(msg)
   puts msg if $verbose
 end
 
+$aborted = false
+
 def command(*args)
   log "$ #{args.join(' ')}"
   output, status = Open3.capture2e(*args)
   if !status.success?
-    warn "Command failed. Aborting."
-    error.output = output.each_line { |line| "  > #{line}" }
-    raise { output: output, status: status }
+    output = output.each_line { |line| "  > #{line}" }
+    unless $aborted
+      $aborted = true
+      warn "Command failed. Aborting."
+      raise output
+    else
+      warn output
+      exit 1
+    end
   end
 end
 
@@ -100,29 +108,29 @@ begin
   command('docker', 'ps')
 
   # Ensure the given URL is an HTTPS link
-  parts    = parse_url $url
-  https    = "https://#{parts[:host]}/#{parts[:user]}/#{parts[:repo]}"
-  repo_new = "vendor/grammars/#{parts[:repo]}"
-  repo_old = parse_submodule($replace) if $replace
+  parts     = parse_url $url
+  $https    = "https://#{parts[:host]}/#{parts[:user]}/#{parts[:repo]}"
+  $repo_new = "vendor/grammars/#{parts[:repo]}"
+  $repo_old = parse_submodule($replace) if $replace
 
   Dir.chdir(ROOT)
 
-  if repo_old
-    log "Deregistering: #{repo_old}"
-    command('git', 'submodule', 'deinit', repo_old)
-    command('git', 'rm', '-rf', repo_old)
+  if $repo_old
+    log "Deregistering: #{$repo_old}"
+    command('git', 'submodule', 'deinit', $repo_old)
+    command('git', 'rm', '-rf', $repo_old)
     command('script/grammar-compiler', 'update', '-f')
   end
 
-  log "Registering new submodule: #{repo_new}"
-  command('git', 'submodule', 'add', '-f', https, repo_new)
-  command('script/grammar-compiler', 'add', repo_new)
+  log "Registering new submodule: #{$repo_new}"
+  command('git', 'submodule', 'add', '-f', $https, $repo_new)
+  command('script/grammar-compiler', 'add', $repo_new)
 
   log "Confirming license"
-  if repo_old
+  if $repo_old
     command('script/licensed')
   else
-    command('script/licensed', '--module', repo_new)
+    command('script/licensed', '--module', $repo_new)
   end
 
   log "Updating grammar documentation in vendor/README.md"
@@ -130,17 +138,21 @@ begin
   command('script/sort-submodules')
   command('script/list-grammars')
 rescue => ex
-  if repo_new
-    `git submodule deinit #{repo_new}`
-    `rm -rf #{repo_new}`
-    `rm -rf .git/modules/#{repo_new}/`
+  log ex
+  if $repo_new
+    `git reset HEAD .gitmodules #{$repo_new}`
+    `git checkout -- vendor/licenses`
+    `rm -rf #{$repo_new}`
+    `rm -rf .git/modules/#{$repo_new}/`
     restore_configs()
   end
-  if repo_old
-    `rm -rf #{repo_old}`
-    `git submodule add -f "#{https}", "#{repo_old}"`
+  if $repo_old
+    `rm -rf #{$repo_old}`
+    `git submodule add -f "#{$https}", "#{$repo_old}"`
     restore_configs()
   end
   File.write("#{ROOT}/vendor/README.md", $vendor_list)
+  `git reset HEAD vendor/licenses`
+  `git checkout -- vendor/licenses`
   exit 1
 end