diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/SpringCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/SpringCodegen.java
index 4b41f4bf64d4..78b7075c667c 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/SpringCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/SpringCodegen.java
@@ -221,6 +221,8 @@ public void processOpts() {
 
         if (additionalProperties.containsKey(ASYNC)) {
             this.setAsync(Boolean.valueOf(additionalProperties.get(ASYNC).toString()));
+            //fix for issue/1164
+            convertPropertyToBooleanAndWriteBack(ASYNC);
         }
 
         if (additionalProperties.containsKey(REACTIVE)) {