diff --git a/tools/generator/autorest/generationMetadata.go b/tools/generator/autorest/generationMetadata.go
index b18d9c9e4566..7c2767a2b7f4 100644
--- a/tools/generator/autorest/generationMetadata.go
+++ b/tools/generator/autorest/generationMetadata.go
@@ -18,21 +18,25 @@ import (
 // GenerationMetadata contains all the metadata that has been used when generating a track 1 package
 type GenerationMetadata struct {
 	// AutorestVersion is the version of autorest.core
-	AutorestVersion      string                 `json:"autorest,omitempty"`
+	AutorestVersion string `json:"autorest,omitempty"`
 	// CommitHash is the commit hash of azure-rest-api-specs from which this SDK package is generated
-	CommitHash           string                 `json:"commit,omitempty"`
+	CommitHash string `json:"commit,omitempty"`
 	// Readme is the normalized path of the readme file from which this SDK package is generated. It should be in this pattern: /_/azure-rest-api-specs/{relative_path}
-	Readme               string                 `json:"readme,omitempty"`
+	Readme string `json:"readme,omitempty"`
 	// Tag is the tag from which this SDK package is generated
-	Tag                  string                 `json:"tag,omitempty"`
+	Tag string `json:"tag,omitempty"`
 	// CodeGenVersion is the version of autorest.go using when this package is generated
-	CodeGenVersion       string                 `json:"use,omitempty"`
+	CodeGenVersion string `json:"use,omitempty"`
 	// RepositoryURL is the URL of the azure-rest-api-specs. This should always be a constant "https://github.com/Azure/azure-rest-api-specs.git"
-	RepositoryURL        string                 `json:"repository_url,omitempty"`
+	RepositoryURL string `json:"repository_url,omitempty"`
 	// AutorestCommand is the full command that generates this package
-	AutorestCommand      string                 `json:"autorest_command,omitempty"`
+	AutorestCommand string `json:"autorest_command,omitempty"`
 	// AdditionalProperties is a map of addition information in this metadata
-	AdditionalProperties map[string]interface{} `json:"additional_properties,omitempty"`
+	AdditionalProperties GenerationMetadataAdditionalProperties `json:"additional_properties,omitempty"`
+}
+
+type GenerationMetadataAdditionalProperties struct {
+	AdditionalOptions string `json:"additional_options,omitempty"`
 }
 
 // RelativeReadme returns the relative readme path
diff --git a/tools/generator/cmd/metadata.go b/tools/generator/cmd/metadata.go
index 2243129cae71..895e3b51d25c 100644
--- a/tools/generator/cmd/metadata.go
+++ b/tools/generator/cmd/metadata.go
@@ -64,8 +64,8 @@ func (ctx changelogContext) process(metadataLocation string) ([]autorest.Changel
 		metadata := ctx.commonMetadata
 		metadata.Tag = result.Tag
 		options := additionalOptions(ctx.autorestArguments)
-		metadata.AdditionalProperties = map[string]interface{}{
-			"additional_options": strings.Join(options, " "),
+		metadata.AdditionalProperties = autorest.GenerationMetadataAdditionalProperties{
+			AdditionalOptions: strings.Join(options, " "),
 		}
 		metadata.AutorestCommand = fmt.Sprintf("autorest --tag=%s --go-sdk-folder=/_/azure-sdk-for-go %s /_/azure-rest-api-specs/%s",
 			result.Tag, strings.Join(options, " "), utils.NormalizePath(ctx.readme))