diff --git a/plugins/better-alias/balias.fish b/plugins/better-alias/balias.fish
index d818791..a80c725 100644
--- a/plugins/better-alias/balias.fish
+++ b/plugins/better-alias/balias.fish
@@ -1,11 +1,10 @@
 function balias --argument alias command
   eval 'alias $alias $command'
-  if expr match $command '^sudo '>/dev/null
-    set command (expr substr + $command 6 (expr length $command))
+  if expr $command : '^sudo '>/dev/null
+    set command (echo "$command" | cut -c6-)
   end
   complete -c $alias -xa "(
     set -l cmd (commandline -pc | sed -e 's/^ *\S\+ *//' );
     complete -C\"$command \$cmd\";
   )"
 end
-
diff --git a/plugins/better-alias/balias.spec.fish b/plugins/better-alias/balias.spec.fish
new file mode 100644
index 0000000..8b869a8
--- /dev/null
+++ b/plugins/better-alias/balias.spec.fish
@@ -0,0 +1,36 @@
+import plugins/fish-spec
+import plugins/balias
+
+function describe_library -d "better-alias"
+
+  function after_all
+    functions -e changedir
+    functions -e ls_as_root
+  end
+
+  function it_doesnt_fail
+    balias changedir cd
+    expect test $status --to-be-true
+  end
+
+  function it_defines_an_alias
+    functions changedir
+    expect test $status --to-be-true
+  end
+
+  function you_can_use_the_alias
+    mkdir testdir
+    changedir testdir
+    expect test $status --to-be-true
+    cd ..
+    rmdir testdir
+  end
+
+  function it_chops_off_sudo
+    balias ls_as_root 'sudo ls'
+    expect test $status --to-be-true
+  end
+
+end
+
+spec.run $argv
\ No newline at end of file