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 57b1e5f12728..fcdcd87ffa99 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
@@ -67,12 +67,12 @@ import kotlinx.serialization.*
         /**
          * Converts the provided [data] to a [String] on success, null otherwise.
          */
-        fun encode(data: Any?): kotlin.String? = if (data is {{classname}}) "$data" else null
+        fun encode(data: kotlin.Any?): kotlin.String? = if (data is {{classname}}) "$data" else null
 
         /**
          * Returns a valid [{{classname}}] for [data], null otherwise.
          */
-        fun decode(data: Any?): {{classname}}? = data?.let {
+        fun decode(data: kotlin.Any?): {{classname}}? = data?.let {
           val normalizedData = "$it".lowercase()
           values().firstOrNull { value ->
             it == value || normalizedData == "$value".lowercase()
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 aa6831225a20..4d9fa1abd645 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
@@ -50,12 +50,12 @@ enum class PetEnum(val value: kotlin.String) {
         /**
          * Converts the provided [data] to a [String] on success, null otherwise.
          */
-        fun encode(data: Any?): kotlin.String? = if (data is PetEnum) "$data" else null
+        fun encode(data: kotlin.Any?): kotlin.String? = if (data is PetEnum) "$data" else null
 
         /**
          * Returns a valid [PetEnum] for [data], null otherwise.
          */
-        fun decode(data: Any?): PetEnum? = data?.let {
+        fun decode(data: kotlin.Any?): PetEnum? = data?.let {
           val normalizedData = "$it".lowercase()
           values().firstOrNull { value ->
             it == value || normalizedData == "$value".lowercase()