diff --git a/modules/openapi-generator/src/main/resources/r/api_client.mustache b/modules/openapi-generator/src/main/resources/r/api_client.mustache
index 4cb754f9849199a0dfd6d385d62a987b53afc595..3beafeb79bbfd0dd9b3de14c666b555f6de16655 100644
--- a/modules/openapi-generator/src/main/resources/r/api_client.mustache
+++ b/modules/openapi-generator/src/main/resources/r/api_client.mustache
@@ -125,6 +125,7 @@ ApiClient  <- R6::R6Class(
     #' @param query_params The query parameters.
     #' @param header_params The header parameters.
     #' @param body The HTTP request body.
+    #' @param stream_callback Callback function to process the data stream
     #' @param ... Other optional arguments.
     #' @return HTTP response
     #' @export
@@ -162,7 +163,7 @@ ApiClient  <- R6::R6Class(
     #' @param query_params The query parameters.
     #' @param header_params The header parameters.
     #' @param body The HTTP request body.
-    #' @param stream_callback callback function to process data stream
+    #' @param stream_callback Callback function to process data stream
     #' @param ... Other optional arguments.
     #' @return HTTP response
     #' @export
diff --git a/samples/client/petstore/R/R/api_client.R b/samples/client/petstore/R/R/api_client.R
index c60b8df2e9fbe25eb4f8677c849d3bf0bef9fe6e..c3c0ac8fd6feff7878d7f1ad96202a0ff20add5a 100644
--- a/samples/client/petstore/R/R/api_client.R
+++ b/samples/client/petstore/R/R/api_client.R
@@ -130,6 +130,7 @@ ApiClient  <- R6::R6Class(
     #' @param query_params The query parameters.
     #' @param header_params The header parameters.
     #' @param body The HTTP request body.
+    #' @param stream_callback Callback function to process the data stream
     #' @param ... Other optional arguments.
     #' @return HTTP response
     #' @export
@@ -167,7 +168,7 @@ ApiClient  <- R6::R6Class(
     #' @param query_params The query parameters.
     #' @param header_params The header parameters.
     #' @param body The HTTP request body.
-    #' @param stream_callback callback function to process data stream
+    #' @param stream_callback Callback function to process data stream
     #' @param ... Other optional arguments.
     #' @return HTTP response
     #' @export