diff --git a/common/config.go b/common/config.go
index a7675b979..1cd75d300 100644
--- a/common/config.go
+++ b/common/config.go
@@ -32,9 +32,8 @@ const productVariablesFileName = "soong.variables"
 type FileConfigurableOptions struct {
 }
 
-func (FileConfigurableOptions) DefaultConfig() jsonConfigurable {
-	f := FileConfigurableOptions{}
-	return f
+func (f *FileConfigurableOptions) SetDefaultConfig() {
+	*f = FileConfigurableOptions{}
 }
 
 type Config struct {
@@ -58,7 +57,7 @@ type config struct {
 }
 
 type jsonConfigurable interface {
-	DefaultConfig() jsonConfigurable
+	SetDefaultConfig()
 }
 
 func loadConfig(config *config) error {
@@ -80,7 +79,8 @@ func loadFromConfigFile(configurable jsonConfigurable, filename string) error {
 		// a dependency tracking loop.
 		// Make a file-configurable-options with defaults, write it out using
 		// a json writer.
-		err = saveToConfigFile(configurable.DefaultConfig(), filename)
+		configurable.SetDefaultConfig()
+		err = saveToConfigFile(configurable, filename)
 		if err != nil {
 			return err
 		}
diff --git a/common/variable.go b/common/variable.go
index 5116a9512..a395b41ba 100644
--- a/common/variable.go
+++ b/common/variable.go
@@ -84,8 +84,8 @@ func stringPtr(v string) *string {
 	return &v
 }
 
-func (productVariables) DefaultConfig() jsonConfigurable {
-	v := productVariables{
+func (v *productVariables) SetDefaultConfig() {
+	*v = productVariables{
 		Device_uses_jemalloc:       boolPtr(true),
 		Platform_sdk_version:       intPtr(22),
 		HostArch:                   stringPtr("x86_64"),
@@ -98,7 +98,6 @@ func (productVariables) DefaultConfig() jsonConfigurable {
 		DeviceSecondaryCpuVariant:  stringPtr("cortex-a15"),
 		DeviceSecondaryAbi:         &[]string{"armeabi-v7a"},
 	}
-	return v
 }
 
 func VariableMutator(mctx blueprint.EarlyMutatorContext) {