diff --git a/modules/openapi-generator/src/main/resources/kotlin-client/enum_class.mustache b/modules/openapi-generator/src/main/resources/kotlin-client/enum_class.mustache
index 3a45715a03c..7d3793d57e5 100644
--- a/modules/openapi-generator/src/main/resources/kotlin-client/enum_class.mustache
+++ b/modules/openapi-generator/src/main/resources/kotlin-client/enum_class.mustache
@@ -74,7 +74,7 @@ import kotlinx.serialization.*
      * This solves a problem when the variable name and its value are different, and ensures that
      * the client sends the correct enum values to the server always.
      */
-    override fun toString(): String = value{{^isString}}.toString(){{/isString}}
+    override fun toString(): kotlin.String = value{{^isString}}.toString(){{/isString}}
 
     companion object {
         /**
diff --git a/samples/client/petstore/kotlin-uppercase-enum/src/main/kotlin/org/openapitools/client/models/PetEnum.kt b/samples/client/petstore/kotlin-uppercase-enum/src/main/kotlin/org/openapitools/client/models/PetEnum.kt
index f25afb05bf2..882b8ff106b 100644
--- a/samples/client/petstore/kotlin-uppercase-enum/src/main/kotlin/org/openapitools/client/models/PetEnum.kt
+++ b/samples/client/petstore/kotlin-uppercase-enum/src/main/kotlin/org/openapitools/client/models/PetEnum.kt
@@ -48,7 +48,7 @@ enum class PetEnum(val value: kotlin.String) {
      * This solves a problem when the variable name and its value are different, and ensures that
      * the client sends the correct enum values to the server always.
      */
-    override fun toString(): String = value
+    override fun toString(): kotlin.String = value
 
     companion object {
         /**