diff --git a/rust/rust.go b/rust/rust.go
index 3d70121..21da5ae 100644
--- a/rust/rust.go
+++ b/rust/rust.go
@@ -1065,6 +1065,9 @@
 	return String(mod.Properties.Min_sdk_version)
 }
 
+var _ android.ApexModule = (*Module)(nil)
+
+// Implements android.ApexModule
 func (mod *Module) ShouldSupportSdkVersion(ctx android.BaseModuleContext, sdkVersion android.ApiLevel) error {
 	minSdkVersion := mod.minSdkVersion()
 	if minSdkVersion == "apex_inherit" {
@@ -1087,6 +1090,7 @@
 	return nil
 }
 
+// Implements android.ApexModule
 func (mod *Module) DepIsInSameApex(ctx android.BaseModuleContext, dep android.Module) bool {
 	depTag := ctx.OtherModuleDependencyTag(dep)