diff --git a/java/bootclasspath.go b/java/bootclasspath.go
index f03a673..f1a0bb5 100644
--- a/java/bootclasspath.go
+++ b/java/bootclasspath.go
@@ -69,13 +69,13 @@
 // addDependencyOntoApexModulePair adds a dependency onto the specified APEX specific variant or the
 // specified module.
 //
-// If apex="platform" then this adds a dependency onto the platform variant of the module. This adds
-// dependencies onto the prebuilt and source modules with the specified name, depending on which
-// ones are available. Visiting must use isActiveModule to select the preferred module when both
-// source and prebuilt modules are available.
+// If apex="platform" or "system_ext" then this adds a dependency onto the platform variant of the
+// module. This adds dependencies onto the prebuilt and source modules with the specified name,
+// depending on which ones are available. Visiting must use isActiveModule to select the preferred
+// module when both source and prebuilt modules are available.
 func addDependencyOntoApexModulePair(ctx android.BottomUpMutatorContext, apex string, name string, tag blueprint.DependencyTag) {
 	var variations []blueprint.Variation
-	if apex != "platform" {
+	if apex != "platform" && apex != "system_ext" {
 		// Pick the correct apex variant.
 		variations = []blueprint.Variation{
 			{Mutator: "apex", Variation: apex},
@@ -124,6 +124,9 @@
 	//
 	// If this is not specified then it defaults to "platform" which will cause a dependency to be
 	// added to the module's platform variant.
+	//
+	// A value of system_ext should be used for any module that will be part of the system_ext
+	// partition.
 	Apex *string
 
 	// The name of the module.