diff --git a/modules/openapi-generator-gradle-plugin/README.adoc b/modules/openapi-generator-gradle-plugin/README.adoc
index 7d082a0fb03..a28290e8c61 100644
--- a/modules/openapi-generator-gradle-plugin/README.adoc
+++ b/modules/openapi-generator-gradle-plugin/README.adoc
@@ -215,7 +215,7 @@ apply plugin: 'org.openapi.generator'
 |Sets mappings between OpenAPI spec types and generated code types.
 
 |additionalProperties
-|Map(String,String)
+|Map(String,Any)
 |None
 |Sets additional properties that can be referenced by the mustache templates.
 
diff --git a/modules/openapi-generator-gradle-plugin/src/main/kotlin/org/openapitools/generator/gradle/plugin/extensions/OpenApiGeneratorGenerateExtension.kt b/modules/openapi-generator-gradle-plugin/src/main/kotlin/org/openapitools/generator/gradle/plugin/extensions/OpenApiGeneratorGenerateExtension.kt
index 4029ab9c434..46aa9540cfa 100644
--- a/modules/openapi-generator-gradle-plugin/src/main/kotlin/org/openapitools/generator/gradle/plugin/extensions/OpenApiGeneratorGenerateExtension.kt
+++ b/modules/openapi-generator-gradle-plugin/src/main/kotlin/org/openapitools/generator/gradle/plugin/extensions/OpenApiGeneratorGenerateExtension.kt
@@ -119,7 +119,7 @@ open class OpenApiGeneratorGenerateExtension(project: Project) {
     /**
      * Sets additional properties that can be referenced by the mustache templates.
      */
-    val additionalProperties = project.objects.mapProperty<String, String>()
+    val additionalProperties = project.objects.mapProperty<String, Any>()
 
     /**
      * Sets server variable for server URL template substitution, in the format of name=value,name=value.
diff --git a/modules/openapi-generator-gradle-plugin/src/main/kotlin/org/openapitools/generator/gradle/plugin/tasks/GenerateTask.kt b/modules/openapi-generator-gradle-plugin/src/main/kotlin/org/openapitools/generator/gradle/plugin/tasks/GenerateTask.kt
index 3de69d41f53..b1dcd474ae8 100644
--- a/modules/openapi-generator-gradle-plugin/src/main/kotlin/org/openapitools/generator/gradle/plugin/tasks/GenerateTask.kt
+++ b/modules/openapi-generator-gradle-plugin/src/main/kotlin/org/openapitools/generator/gradle/plugin/tasks/GenerateTask.kt
@@ -189,7 +189,7 @@ open class GenerateTask : DefaultTask() {
      */
     @Optional
     @Input
-    val additionalProperties = project.objects.mapProperty<String, String>()
+    val additionalProperties = project.objects.mapProperty<String, Any>()
 
     /**
      * Sets server variable for server URL template substitution, in the format of name=value,name=value.