diff --git a/airframe-http-codegen/src/main/scala/wvlet/airframe/http/codegen/HttpClientIR.scala b/airframe-http-codegen/src/main/scala/wvlet/airframe/http/codegen/HttpClientIR.scala
index ae66284c2..c6502a189 100644
--- a/airframe-http-codegen/src/main/scala/wvlet/airframe/http/codegen/HttpClientIR.scala
+++ b/airframe-http-codegen/src/main/scala/wvlet/airframe/http/codegen/HttpClientIR.scala
@@ -184,6 +184,17 @@ object HttpClientIR extends LogSupport {
         )
         .map(arg => HttpClientGenerator.fullTypeNameOf(arg))
         .mkString(", ")
+
+    def rpcReturnElementType: Surface = {
+      val isRxResponse = returnType.rawType.isAssignableFrom(classOf[Rx[_]]) && returnType.typeArgs.size == 1
+      if (isRxResponse) {
+        // for methods returning Rx[A], extract A
+        returnType.typeArgs(0)
+      } else {
+        returnType
+      }
+    }
+
     def clientMethodName = {
       val methodName = httpMethod.toString.toLowerCase(Locale.ENGLISH)
       if (isOpsRequest) s"${methodName}Ops"
diff --git a/airframe-http-codegen/src/main/scala/wvlet/airframe/http/codegen/client/RPCClientGenerator.scala b/airframe-http-codegen/src/main/scala/wvlet/airframe/http/codegen/client/RPCClientGenerator.scala
index 647806833..453a506a3 100644
--- a/airframe-http-codegen/src/main/scala/wvlet/airframe/http/codegen/client/RPCClientGenerator.scala
+++ b/airframe-http-codegen/src/main/scala/wvlet/airframe/http/codegen/client/RPCClientGenerator.scala
@@ -17,6 +17,7 @@ import wvlet.airframe.http.codegen.HttpClientIR
 import wvlet.airframe.http.codegen.HttpClientIR.{ClientMethodDef, ClientServiceDef}
 import wvlet.airframe.http.codegen.client.HttpClientGenerator.RichSurface
 import wvlet.airframe.rx.Rx
+import wvlet.airframe.surface.Surface
 
 /**
   * The default RPC client generator using Http.client.Sync/AsyncClient
@@ -71,7 +72,7 @@ object RPCClientGenerator extends HttpClientGenerator {
     def rpcMethodDefs(svc: ClientServiceDef): String = {
       svc.methods
         .map { m =>
-          s"""lazy val __m_${m.name} = RPCMethod("${m.path}", "${svc.interfaceName}", "${m.name}", Surface.of[${m.requestModelClassType}], Surface.of[${m.returnType.fullTypeName}])"""
+          s"""lazy val __m_${m.name} = RPCMethod("${m.path}", "${svc.interfaceName}", "${m.name}", Surface.of[${m.requestModelClassType}], Surface.of[${m.rpcReturnElementType.fullTypeName}])"""
         }.mkString("\n")
     }
 
@@ -142,13 +143,7 @@ object RPCClientGenerator extends HttpClientGenerator {
             m.inputParameters
               .map(x => s"${x.name}: ${x.surface.fullTypeName}")
 
-          val isRxResponse = m.returnType.rawType.isAssignableFrom(classOf[Rx[_]]) && m.returnType.typeArgs.size == 1
-          val returnElementType = if (isRxResponse) {
-            // for methods returning Rx[A], extract A
-            m.returnType.typeArgs(0).fullTypeName
-          } else {
-            m.returnType.fullTypeName
-          }
+          val returnElementType = m.rpcReturnElementType.fullTypeName
           val returnType =
             if (isAsync)
               s"Rx[${returnElementType}]"