diff --git a/modules/swagger-codegen/src/main/resources/kotlin-client/infrastructure/ApiClient.kt.mustache b/modules/swagger-codegen/src/main/resources/kotlin-client/infrastructure/ApiClient.kt.mustache
index 6c56fd17356..e46256a3567 100644
--- a/modules/swagger-codegen/src/main/resources/kotlin-client/infrastructure/ApiClient.kt.mustache
+++ b/modules/swagger-codegen/src/main/resources/kotlin-client/infrastructure/ApiClient.kt.mustache
@@ -85,9 +85,9 @@ open class ApiClient(val baseUrl: String) {
             RequestMethod.DELETE -> Request.Builder().url(url).delete()
             RequestMethod.GET -> Request.Builder().url(url)
             RequestMethod.HEAD -> Request.Builder().url(url).head()
-            RequestMethod.PATCH -> Request.Builder().url(url).patch(requestBody(body!!, contentType))
-            RequestMethod.PUT -> Request.Builder().url(url).put(requestBody(body!!, contentType))
-            RequestMethod.POST -> Request.Builder().url(url).post(requestBody(body!!, contentType))
+            RequestMethod.PATCH -> Request.Builder().url(url).patch(requestBody(body, contentType))
+            RequestMethod.PUT -> Request.Builder().url(url).put(requestBody(body, contentType))
+            RequestMethod.POST -> Request.Builder().url(url).post(requestBody(body, contentType))
             RequestMethod.OPTIONS -> Request.Builder().url(url).method("OPTIONS", null)
         }
 
diff --git a/samples/client/petstore/kotlin/src/main/kotlin/io/swagger/client/infrastructure/ApiClient.kt b/samples/client/petstore/kotlin/src/main/kotlin/io/swagger/client/infrastructure/ApiClient.kt
index da178750688..eb13afafce6 100644
--- a/samples/client/petstore/kotlin/src/main/kotlin/io/swagger/client/infrastructure/ApiClient.kt
+++ b/samples/client/petstore/kotlin/src/main/kotlin/io/swagger/client/infrastructure/ApiClient.kt
@@ -85,9 +85,9 @@ open class ApiClient(val baseUrl: String) {
             RequestMethod.DELETE -> Request.Builder().url(url).delete()
             RequestMethod.GET -> Request.Builder().url(url)
             RequestMethod.HEAD -> Request.Builder().url(url).head()
-            RequestMethod.PATCH -> Request.Builder().url(url).patch(requestBody(body!!, contentType))
-            RequestMethod.PUT -> Request.Builder().url(url).put(requestBody(body!!, contentType))
-            RequestMethod.POST -> Request.Builder().url(url).post(requestBody(body!!, contentType))
+            RequestMethod.PATCH -> Request.Builder().url(url).patch(requestBody(body, contentType))
+            RequestMethod.PUT -> Request.Builder().url(url).put(requestBody(body, contentType))
+            RequestMethod.POST -> Request.Builder().url(url).post(requestBody(body, contentType))
             RequestMethod.OPTIONS -> Request.Builder().url(url).method("OPTIONS", null)
         }