diff --git a/src/compiler/commandLineParser.ts b/src/compiler/commandLineParser.ts
index fa2826598ad..1f57c142113 100644
--- a/src/compiler/commandLineParser.ts
+++ b/src/compiler/commandLineParser.ts
@@ -242,12 +242,14 @@ namespace ts {
         }        
     ];
 
+    /* @internal */
     export interface OptionNameMap {
         optionNameMap: Map<CommandLineOption>;
         shortOptionNames: Map<string>;
     }
 
     let optionNameMapCache: OptionNameMap;
+    /* @internal */
     export function getOptionNameMap(): OptionNameMap {
         if (optionNameMapCache) {
             return optionNameMapCache;
diff --git a/src/compiler/program.ts b/src/compiler/program.ts
index 596a2b7170a..36700e0fbf5 100644
--- a/src/compiler/program.ts
+++ b/src/compiler/program.ts
@@ -225,6 +225,7 @@ namespace ts {
         return { resolvedFileName: referencedSourceFile, failedLookupLocations };
     }
 
+    /* @internal */
     export const defaultInitCompilerOptions: CompilerOptions = {
         module: ModuleKind.CommonJS,
         target: ScriptTarget.ES3,
@@ -234,6 +235,7 @@ namespace ts {
         sourceMap: false,
     }
 
+    /* @internal */
     export function scriptTargetToString(target: ScriptTarget): string {
         switch (target) {
             case ScriptTarget.ES5:
@@ -245,6 +247,7 @@ namespace ts {
         }
     }
 
+    /* @internal */
     export function moduleKindToString(kind: ModuleKind): string {
         switch (kind) {
             case ModuleKind.None:
@@ -260,6 +263,7 @@ namespace ts {
         }
     }
 
+    /* @internal */
     export function newLineKindToString(kind: NewLineKind): string {
         switch (kind) {
             case NewLineKind.CarriageReturnLineFeed:
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index 72b948b96d0..dfa44859266 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -2109,6 +2109,7 @@ namespace ts {
         errors: Diagnostic[];
     }
 
+    /* @internal */
     export interface CommandLineOption {
         name: string;
         type: string | Map<number>;         // "string", "number", "boolean", or an object literal mapping named values to actual values