diff --git a/packages/caching-compiler/caching-compiler.js b/packages/caching-compiler/caching-compiler.js
index 9da097afd7..ab1cea5cae 100644
--- a/packages/caching-compiler/caching-compiler.js
+++ b/packages/caching-compiler/caching-compiler.js
@@ -277,7 +277,7 @@ CachingCompiler = class CachingCompiler extends CachingCompilerBase {
   // you have processing you want to perform at the beginning or end of a
   // processing phase, you may want to override this method and call the
   // superclass implementation from within your method.
-  processFilesForTarget(inputFiles) {
+  async processFilesForTarget(inputFiles) {
     const cacheMisses = [];
     const arches = this._cacheDebugEnabled && Object.create(null);
 
diff --git a/packages/caching-compiler/multi-file-caching-compiler.js b/packages/caching-compiler/multi-file-caching-compiler.js
index 8ab5a99993..4add6b81a3 100644
--- a/packages/caching-compiler/multi-file-caching-compiler.js
+++ b/packages/caching-compiler/multi-file-caching-compiler.js
@@ -78,7 +78,7 @@ extends CachingCompilerBase {
   }
 
   // The processFilesForTarget method from the Plugin.registerCompiler API.
-  processFilesForTarget(inputFiles) {
+  async processFilesForTarget(inputFiles) {
     const allFiles = new Map;
     const cacheKeyMap = new Map;
     const cacheMisses = [];