diff --git a/plugins/commands/serve/client/communicator.rb b/plugins/commands/serve/client/communicator.rb
index 169b9d96e..0f7ec906b 100644
--- a/plugins/commands/serve/client/communicator.rb
+++ b/plugins/commands/serve/client/communicator.rb
@@ -4,6 +4,7 @@ module VagrantPlugins
     module Client
       class Communicator
 
+        prepend Util::HasMapper
         extend Util::Connector
         include Util::HasSeeds::Client
 
@@ -177,10 +178,7 @@ module VagrantPlugins
         protected
 
         def generate_execution_request(machine, cmd, opts={})
-          opts.transform_values! { |v| v.is_a?(Symbol) ? v.to_s : v}
-          opts_struct = Google::Protobuf::Struct.from_hash(
-            opts.transform_keys(&:to_s)
-          )
+          opts_proto = mapper.map(opts, to: SDK::Args::Hash)
 
           SDK::FuncSpec::Args.new(
             args: [
@@ -194,8 +192,8 @@ module VagrantPlugins
                 value: Google::Protobuf::Any.pack(SDK::Communicator::Command.new(command: cmd)),
               ),
               SDK::FuncSpec::Value.new(
-                type: "google.protobuf.Struct",
-                value: Google::Protobuf::Any.pack(opts_struct),
+                type: "hashicorp.vagrant.sdk.Args.Hash",
+                value: Google::Protobuf::Any.pack(opts_proto),
               ),
             ]
           )
diff --git a/plugins/commands/serve/mappers/known_types.rb b/plugins/commands/serve/mappers/known_types.rb
index 0f4de83e1..4949563d3 100644
--- a/plugins/commands/serve/mappers/known_types.rb
+++ b/plugins/commands/serve/mappers/known_types.rb
@@ -51,6 +51,24 @@ module VagrantPlugins
         end
       end
 
+      class HashProtoFromSpec < Mapper
+        def initialize
+          super(
+            inputs: [Input.new(type: SDK::FuncSpec::Value) { |arg|
+                arg.type == "hashicorp.vagrant.sdk.Args.Hash" &&
+                  !arg&.value&.value.nil?
+              }
+            ],
+            output: SDK::Args::Hash,
+            func: method(:converter),
+          )
+        end
+
+        def converter(fv)
+          SDK::Args::Hash.decode(fv.value.value)
+        end
+      end
+
       class HashFromProto < Mapper
         def initialize
           super(
@@ -65,7 +83,7 @@ module VagrantPlugins
 
         def converter(proto, mapper)
           Hash.new.tap do |result|
-            proto.fields.each_pair do |k, v|
+            proto.fields.each do |k, v|
               r = mapper.map(v)
               result[k.to_s] = r
             end
diff --git a/plugins/commands/serve/service/communicator_service.rb b/plugins/commands/serve/service/communicator_service.rb
index 271f46c05..bd333d343 100644
--- a/plugins/commands/serve/service/communicator_service.rb
+++ b/plugins/commands/serve/service/communicator_service.rb
@@ -260,7 +260,7 @@ module VagrantPlugins
                 name: "",
               ),
               SDK::FuncSpec::Value.new(
-                type: "google.protobuf.Struct",
+                type: "hashicorp.vagrant.sdk.Args.Hash",
                 name: "",
               )
             ],
@@ -274,15 +274,14 @@ module VagrantPlugins
         def privileged_execute(req, ctx)
           with_info(ctx) do |info|
             plugin_name = info.plugin_name
-            target, cmd, opts = mapper.funcspec_map(req, mapper, broker)
-            logger.debug("Got machine client #{target}")
+            machine, cmd, opts = mapper.funcspec_map(
+              req, mapper, broker,
+              expect: [Vagrant::Machine, SDK::Communicator::Command, Hash]
+            )
+            logger.debug("Got machine client #{machine}")
             logger.debug("Got opts #{opts}")
             logger.debug("Got cmd #{cmd}")
 
-            project = target.project
-            env = Vagrant::Environment.new({client: project})
-            machine = env.machine(target.name.to_sym, target.provider_name.to_sym)
-
             plugin = Vagrant.plugin("2").manager.communicators[plugin_name.to_s.to_sym]
             communicator = plugin.new(machine)
             exit_code = communicator.sudo(cmd.command, opts)