diff --git a/nac3artiq/src/codegen.rs b/nac3artiq/src/codegen.rs
index 72b55aa7..77b1fd98 100644
--- a/nac3artiq/src/codegen.rs
+++ b/nac3artiq/src/codegen.rs
@@ -12,7 +12,7 @@ use nac3core::{
     },
     symbol_resolver::ValueEnum,
     toplevel::{helper::PrimDef, numpy::unpack_ndarray_var_tys, DefinitionId, GenCall},
-    typecheck::typedef::{iter_type_vars, FunSignature, FuncArg, Type, TypeEnum, VarMap},
+    typecheck::typedef::{iter_type_vars, FunSignature, FuncOption, FuncArg, Type, TypeEnum, VarMap},
 };
 
 use nac3parser::ast::{Expr, ExprKind, Located, Stmt, StmtKind, StrRef};
@@ -831,8 +831,6 @@ fn rpc_codegen_callback_fn<'ctx>(
     let ptr_type = int8.ptr_type(AddressSpace::default());
     let tag_ptr_type = ctx.ctx.struct_type(&[ptr_type.into(), size_type.into()], false);
 
-    // println!("obj: {:?}", obj);
-    println!("fun: {:?}", fun);
 
     let service_id = int32.const_int(fun.1 .0 as u64, false);
     // -- setup rpc tags
@@ -934,36 +932,63 @@ fn rpc_codegen_callback_fn<'ctx>(
         ctx.builder.build_store(arg_ptr, arg_slot).unwrap();
     }
 
+    let is_async = fun.0.opts.iter().any(|opt| FuncOption::Async == *opt);
+
     // call
-    let rpc_send = ctx.module.get_function("rpc_send").unwrap_or_else(|| {
-        ctx.module.add_function(
-            "rpc_send",
-            ctx.ctx.void_type().fn_type(
-                &[
-                    int32.into(),
-                    tag_ptr_type.ptr_type(AddressSpace::default()).into(),
-                    ptr_type.ptr_type(AddressSpace::default()).into(),
-                ],
-                false,
-            ),
-            None,
-        )
-    });
-    ctx.builder
-        .build_call(rpc_send, &[service_id.into(), tag_ptr.into(), args_ptr.into()], "rpc.send")
-        .unwrap();
+    if is_async {
+        let rpc_send_async = ctx.module.get_function("rpc_send_async").unwrap_or_else(|| {
+            ctx.module.add_function(
+                "rpc_send_async",
+                ctx.ctx.void_type().fn_type(
+                    &[
+                        int32.into(),
+                        tag_ptr_type.ptr_type(AddressSpace::default()).into(),
+                        ptr_type.ptr_type(AddressSpace::default()).into(),
+                    ],
+                    false,
+                ),
+                None,
+            )
+        });
+        ctx.builder
+            .build_call(rpc_send_async, &[service_id.into(), tag_ptr.into(), args_ptr.into()], "rpc.send")
+            .unwrap();
+    } else {
+        let rpc_send = ctx.module.get_function("rpc_send").unwrap_or_else(|| {
+            ctx.module.add_function(
+                "rpc_send",
+                ctx.ctx.void_type().fn_type(
+                    &[
+                        int32.into(),
+                        tag_ptr_type.ptr_type(AddressSpace::default()).into(),
+                        ptr_type.ptr_type(AddressSpace::default()).into(),
+                    ],
+                    false,
+                ),
+                None,
+            )
+        });
+        ctx.builder
+            .build_call(rpc_send, &[service_id.into(), tag_ptr.into(), args_ptr.into()], "rpc.send")
+            .unwrap();
+    }
 
     // reclaim stack space used by arguments
     call_stackrestore(ctx, stackptr);
 
-    let result = format_rpc_ret(generator, ctx, fun.0.ret);
-
-    if !result.is_some_and(|res| res.get_type().is_pointer_type()) {
-        // An RPC returning an NDArray would not touch here.
-        call_stackrestore(ctx, stackptr);
+    if is_async {
+        // async RPCs do not return any values
+        Ok(None)
+    } else {
+        let result = format_rpc_ret(generator, ctx, fun.0.ret);
+    
+        if !result.is_some_and(|res| res.get_type().is_pointer_type()) {
+            // An RPC returning an NDArray would not touch here.
+            call_stackrestore(ctx, stackptr);
+        }
+    
+        Ok(result)
     }
-
-    Ok(result)
 }
 
 pub fn attributes_writeback(
diff --git a/nac3artiq/src/lib.rs b/nac3artiq/src/lib.rs
index 5f8463f9..c22990a1 100644
--- a/nac3artiq/src/lib.rs
+++ b/nac3artiq/src/lib.rs
@@ -54,7 +54,7 @@ use nac3core::{
         composer::{BuiltinFuncCreator, BuiltinFuncSpec, ComposerConfig, TopLevelComposer},
         DefinitionId, GenCall, TopLevelDef,
     },
-    typecheck::typedef::{FunSignature, FuncArg},
+    typecheck::typedef::{FunSignature, FuncOption, FuncArg},
     typecheck::{type_inferencer::PrimitiveStore, typedef::Type},
 };
 
@@ -200,7 +200,7 @@ impl Nac3 {
                                         || id.to_string() == "rpc"
                                 } else if let ExprKind::Call { func, .. } = &decorator.node {
                                     // decorators with flags (e.g. rpc async) have Call for the node;
-                                    // this is to remove the middle
+                                    // this is to remove the middle part
                                     if let ExprKind::Name { id, .. } = func.node {
                                         if id.to_string() == "rpc" { 
                                             println!("found rpc: {:?}", func);
@@ -513,7 +513,7 @@ impl Nac3 {
                                         class_name, stmt.location
                                     )));
                                 }
-                                rpc_ids.push((Some((class_obj.clone(), *name)), def_id, Some(FuncFlags::Async)));
+                                rpc_ids.push((Some((class_obj.clone(), *name)), def_id));
                             }
                         }
                     }
@@ -616,7 +616,7 @@ impl Nac3 {
         {
             let rpc_codegen = rpc_codegen_callback();
             let defs = top_level.definitions.read();
-            for (class_data, id, flags) in &rpc_ids {
+            for (class_data, id) in &rpc_ids {
                 let mut def = defs[id.0].write();
                 match &mut *def {
                     TopLevelDef::Function { codegen_callback, .. } => {
diff --git a/nac3core/src/typecheck/typedef/mod.rs b/nac3core/src/typecheck/typedef/mod.rs
index dcb331ae..8837da86 100644
--- a/nac3core/src/typecheck/typedef/mod.rs
+++ b/nac3core/src/typecheck/typedef/mod.rs
@@ -123,8 +123,8 @@ impl FuncArg {
     }
 }
 
-#[derive(Debug, Clone)]
-pub enum FunOption {
+#[derive(PartialEq, Debug, Clone)]
+pub enum FuncOption {
     Async,
 }
 
@@ -133,7 +133,7 @@ pub struct FunSignature {
     pub args: Vec<FuncArg>,
     pub ret: Type,
     pub vars: VarMap,
-    pub opts: Vec<FunOption>,
+    pub opts: Vec<FuncOption>,
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]