diff --git a/internal/tsc_wrapped/cache_test.ts b/internal/tsc_wrapped/cache_test.ts
index e4aeaf3..09e0afa 100644
--- a/internal/tsc_wrapped/cache_test.ts
+++ b/internal/tsc_wrapped/cache_test.ts
@@ -22,7 +22,7 @@
 import {CachedFileLoader, FileCache, ProgramAndFileCache} from './cache';
 import {invalidateFileCache, writeTempFile} from './test_support';
 
-function fauxDebug(...args: any[]) {
+function fauxDebug(...args: [any?, ...any[]]) {
   console.error.apply(console, args);
 }
 
diff --git a/internal/tsc_wrapped/strict_deps_test.ts b/internal/tsc_wrapped/strict_deps_test.ts
index 2b55517..807e86e 100644
--- a/internal/tsc_wrapped/strict_deps_test.ts
+++ b/internal/tsc_wrapped/strict_deps_test.ts
@@ -39,7 +39,7 @@
       if (!files[fileName]) {
         if (astCache.has(fileName)) return astCache.get(fileName);
         const file = originalGetSourceFile(fileName, ts.ScriptTarget.Latest);
-        astCache.set(fileName, file);
+        astCache.set(fileName, file!);
         return file;
       }
       return ts.createSourceFile(