diff --git a/src/server/editorServices.ts b/src/server/editorServices.ts
index 1f8f9d3b21b..dc2fa086a93 100644
--- a/src/server/editorServices.ts
+++ b/src/server/editorServices.ts
@@ -312,7 +312,8 @@ namespace ts.server {
 
     export class ProjectService {
 
-        public readonly typingsCache: TypingsCache;
+        /*@internal*/
+        readonly typingsCache: TypingsCache;
 
         private readonly documentRegistry: DocumentRegistry;
 
diff --git a/src/server/typingsCache.ts b/src/server/typingsCache.ts
index f2642230f2d..6418b5f9cbe 100644
--- a/src/server/typingsCache.ts
+++ b/src/server/typingsCache.ts
@@ -24,7 +24,7 @@ namespace ts.server {
         globalTypingsCacheLocation: undefined
     };
 
-    class TypingsCacheEntry {
+    interface TypingsCacheEntry {
         readonly typeAcquisition: TypeAcquisition;
         readonly compilerOptions: CompilerOptions;
         readonly typings: SortedReadonlyArray<string>;
@@ -80,6 +80,7 @@ namespace ts.server {
         return !arrayIsEqualTo(imports1, imports2);
     }
 
+    /*@internal*/
     export class TypingsCache {
         private readonly perProjectCache: Map<TypingsCacheEntry> = createMap<TypingsCacheEntry>();
 
diff --git a/tests/baselines/reference/api/tsserverlibrary.d.ts b/tests/baselines/reference/api/tsserverlibrary.d.ts
index 2e8e3f3871d..d102f467ade 100644
--- a/tests/baselines/reference/api/tsserverlibrary.d.ts
+++ b/tests/baselines/reference/api/tsserverlibrary.d.ts
@@ -7602,17 +7602,6 @@ declare namespace ts.server {
         readonly globalTypingsCacheLocation: string;
     }
     const nullTypingsInstaller: ITypingsInstaller;
-    class TypingsCache {
-        private readonly installer;
-        private readonly perProjectCache;
-        constructor(installer: ITypingsInstaller);
-        isKnownTypesPackageName(name: string): boolean;
-        installPackage(options: InstallPackageOptionsWithProject): Promise<ApplyCodeActionCommandResult>;
-        getTypingsForProject(project: Project, unresolvedImports: SortedReadonlyArray<string>, forceRefresh: boolean): SortedReadonlyArray<string>;
-        updateTypingsForProject(projectName: string, compilerOptions: CompilerOptions, typeAcquisition: TypeAcquisition, unresolvedImports: SortedReadonlyArray<string>, newTypings: string[]): void;
-        deleteTypingsForProject(projectName: string): void;
-        onProjectClosed(project: Project): void;
-    }
 }
 declare namespace ts.server {
     enum ProjectKind {
@@ -7960,7 +7949,6 @@ declare namespace ts.server {
         syntaxOnly?: boolean;
     }
     class ProjectService {
-        readonly typingsCache: TypingsCache;
         private readonly documentRegistry;
         /**
          * Container of all known scripts