diff --git a/src/compiler/core.ts b/src/compiler/core.ts
index 654e6b00c1a..357bd0699e3 100644
--- a/src/compiler/core.ts
+++ b/src/compiler/core.ts
@@ -1752,6 +1752,7 @@ namespace ts {
         return path.length > extension.length && endsWith(path, extension);
     }
 
+    /* @internal */
     export function fileExtensionIsOneOf(path: string, extensions: string[]): boolean {
         for (const extension of extensions) {
             if (fileExtensionIs(path, extension)) {
diff --git a/src/compiler/moduleNameResolver.ts b/src/compiler/moduleNameResolver.ts
index b1d0f2ab7b2..5c2e2dcea8e 100644
--- a/src/compiler/moduleNameResolver.ts
+++ b/src/compiler/moduleNameResolver.ts
@@ -976,6 +976,7 @@ namespace ts {
         return moduleName;
     }
 
+    /* @internal */
     export function getPackageNameFromAtTypesDirectory(mangledName: string): string {
         const withoutAtTypePrefix = removePrefix(mangledName, "@types/");
         if (withoutAtTypePrefix !== mangledName) {