diff --git a/fsgen/filesystem_creator.go b/fsgen/filesystem_creator.go
index 5ab1b9b..7db70e8 100644
--- a/fsgen/filesystem_creator.go
+++ b/fsgen/filesystem_creator.go
@@ -59,7 +59,7 @@
 }
 
 func (f *filesystemCreator) createInternalModules(ctx android.LoadHookContext) {
-	for _, partitionType := range []string{"system", "system_ext"} {
+	for _, partitionType := range []string{"system"} {
 		if f.createPartition(ctx, partitionType) {
 			f.properties.Generated_partition_types = append(f.properties.Generated_partition_types, partitionType)
 		} else {
@@ -88,14 +88,11 @@
 		Name: proptools.StringPtr(f.generatedModuleName(ctx.Config(), "device")),
 	}
 
-	// Currently, only the system and system_ext partition module is created.
+	// Currently, only the system partition module is created.
 	partitionProps := &filesystem.PartitionNameProperties{}
 	if android.InList("system", f.properties.Generated_partition_types) {
 		partitionProps.System_partition_name = proptools.StringPtr(f.generatedModuleNameForPartition(ctx.Config(), "system"))
 	}
-	if android.InList("system_ext", f.properties.Generated_partition_types) {
-		partitionProps.System_ext_partition_name = proptools.StringPtr(f.generatedModuleNameForPartition(ctx.Config(), "system_ext"))
-	}
 
 	ctx.CreateModule(filesystem.AndroidDeviceFactory, baseProps, partitionProps)
 }
@@ -131,13 +128,11 @@
 
 	fsProps.Partition_name = proptools.StringPtr(partitionType)
 	// BOARD_SYSTEMIMAGE_FILE_SYSTEM_TYPE
-	fsType := specificPartitionVars.BoardFileSystemType
-	if fsType == "" {
-		fsType = "ext4" //default
-	}
-	fsProps.Type = proptools.StringPtr(fsType)
-	if filesystem.GetFsTypeFromString(ctx, *fsProps.Type).IsUnknown() {
-		// Currently the android_filesystem module type only supports a handful of FS types like ext4, erofs
+	fsProps.Type = proptools.StringPtr(specificPartitionVars.BoardFileSystemType)
+	if *fsProps.Type != "ext4" {
+		// TODO(b/372522486): Support other FS types.
+		// Currently the android_filesystem module type only supports ext4:
+		// https://cs.android.com/android/platform/superproject/main/+/main:build/soong/filesystem/filesystem.go;l=416;drc=98047cfd07944b297a12d173453bc984806760d2
 		return false
 	}