diff --git a/src/command_manager.cc b/src/command_manager.cc
index 4902f068..ff4b589a 100644
--- a/src/command_manager.cc
+++ b/src/command_manager.cc
@@ -513,16 +513,20 @@ CommandInfo CommandManager::command_info(const Context& context, StringView comm
 }
 
 Completions CommandManager::complete_command_name(const Context& context,
-                                                  StringView query) const
+                                                  StringView query, bool with_aliases) const
 {
-    auto candidates = Kakoune::complete(
-        query, query.length(), concatenated(
-            m_commands
+    auto commands = m_commands
             | filter([](const CommandMap::value_type& cmd) { return not (cmd.second.flags & CommandFlags::Hidden); })
-            | transform([](const CommandMap::value_type& cmd) { return StringView{cmd.first}; }),
-            context.aliases().flatten_aliases()
-            | transform([](AliasRegistry::AliasDesc alias) { return alias.first; })));
+            | transform([](const CommandMap::value_type& cmd) { return StringView{cmd.first}; });
 
+    if (not with_aliases)
+        return {0, query.length(), Kakoune::complete(query, query.length(), commands)};
+
+    auto candidates = Kakoune::complete(query, query.length(),
+        concatenated(commands,
+                     context.aliases().flatten_aliases()
+                    | transform([](AliasRegistry::AliasDesc alias)
+                                { return alias.first; })));
     return {0, query.length(), std::move(candidates)};
 }
 
@@ -556,7 +560,7 @@ Completions CommandManager::complete(const Context& context,
     {
         auto cmd_start = is_last_token ? cursor_pos : tokens[tok_idx].begin();
         StringView query = command_line.substr(cmd_start, cursor_pos - cmd_start);
-        return offset_pos(complete_command_name(context, query), cmd_start);
+        return offset_pos(complete_command_name(context, query, true), cmd_start);
     }
 
     kak_assert(not tokens.empty());
@@ -625,7 +629,7 @@ Completions CommandManager::complete(const Context& context,
     StringView prefix = params[token_to_complete].substr(0, pos_in_token);
 
     if (token_to_complete == 0)
-        return complete_command_name(context, prefix);
+        return complete_command_name(context, prefix, true);
     else
     {
         const String& command_name = params[0];
diff --git a/src/command_manager.hh b/src/command_manager.hh
index 090ed0fb..4a1c4c01 100644
--- a/src/command_manager.hh
+++ b/src/command_manager.hh
@@ -124,14 +124,14 @@ public:
                           CommandHelper helper = CommandHelper(),
                           CommandCompleter completer = CommandCompleter());
 
+    Completions complete_command_name(const Context& context, StringView query, bool with_aliases) const;
+
 private:
     void execute_single_command(CommandParameters params,
                                 Context& context,
                                 const ShellContext& shell_context,
                                 CharCoord pos) const;
 
-    Completions complete_command_name(const Context& context, StringView query) const;
-
     struct CommandDescriptor
     {
         Command command;
diff --git a/src/commands.cc b/src/commands.cc
index d92f3ee9..a483573b 100644
--- a/src/commands.cc
+++ b/src/commands.cc
@@ -867,6 +867,21 @@ const CommandDesc define_command_cmd = {
     define_command
 };
 
+static Completions complete_scope(const Context&, CompletionFlags,
+                                  const String& prefix, ByteCount cursor_pos)
+{
+   auto scopes = {"global", "buffer", "window"};
+   return { 0_byte, cursor_pos, complete(prefix, cursor_pos, scopes) };
+}
+
+
+static Completions complete_command_name(const Context& context, CompletionFlags,
+                                         const String& prefix, ByteCount cursor_pos)
+{
+   return CommandManager::instance().complete_command_name(
+       context, prefix.substr(0, cursor_pos), false);
+}
+
 const CommandDesc alias_cmd = {
     "alias",
     nullptr,
@@ -874,7 +889,9 @@ const CommandDesc alias_cmd = {
     ParameterDesc{{}, ParameterDesc::Flags::None, 3, 3},
     CommandFlags::None,
     CommandHelper{},
-    CommandCompleter{},
+    PerArgumentCommandCompleter({
+        complete_scope, complete_nothing, complete_command_name
+    }),
     [](const ParametersParser& parser, Context& context, const ShellContext&)
     {
         if (not CommandManager::instance().command_defined(parser[2]))
@@ -893,7 +910,10 @@ const CommandDesc unalias_cmd = {
     ParameterDesc{{}, ParameterDesc::Flags::None, 2, 3},
     CommandFlags::None,
     CommandHelper{},
-    CommandCompleter{},
+    PerArgumentCommandCompleter({
+        complete_scope, complete_nothing, complete_command_name
+
+    }),
     [](const ParametersParser& parser, Context& context, const ShellContext&)
     {
         AliasRegistry& aliases = get_scope(parser[0], context).aliases();