diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index b2a0629cc71..99071469dec 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -1034,7 +1034,6 @@ import {
     TypeReferenceType,
     TypeVariable,
     UnaryExpression,
-    UnderscoreEscapedMap,
     unescapeLeadingUnderscores,
     UnionOrIntersectionType,
     UnionOrIntersectionTypeNode,
@@ -5259,7 +5258,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         exportsWithDuplicate?: ExportDeclaration[];
     }
 
-    type ExportCollisionTrackerTable = UnderscoreEscapedMap<ExportCollisionTracker>;
+    type ExportCollisionTrackerTable = Map<__String, ExportCollisionTracker>;
 
     /**
      * Extends one symbol table with another while collecting information on name collisions for error message generation into the `lookupTable` argument
@@ -5293,7 +5292,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
 
     function getExportsOfModuleWorker(moduleSymbol: Symbol) {
         const visitedSymbols: Symbol[] = [];
-        let typeOnlyExportStarMap: UnderscoreEscapedMap<ExportDeclaration & { readonly isTypeOnly: true }> | undefined;
+        let typeOnlyExportStarMap: Map<__String, ExportDeclaration & { readonly isTypeOnly: true }> | undefined;
         const nonTypeOnlyNames = new Set<__String>();
 
         // A module defined by an 'export=' consists of one export that needs to be resolved
@@ -5706,7 +5705,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                     // The below is used to lookup type parameters within a class or interface, as they are added to the class/interface locals
                     // These can never be latebound, so the symbol's raw members are sufficient. `getMembersOfNode` cannot be used, as it would
                     // trigger resolving late-bound names, which we may already be in the process of doing while we're here!
-                    let table: UnderscoreEscapedMap<Symbol> | undefined;
+                    let table: Map<__String, Symbol> | undefined;
                     // TODO: Should this filtered table be cached in some way?
                     (getSymbolOfDeclaration(location as ClassLikeDeclaration | InterfaceDeclaration).members || emptySymbols).forEach((memberSymbol, key) => {
                         if (memberSymbol.flags & (SymbolFlags.Type & ~SymbolFlags.Assignment)) {
@@ -12354,7 +12353,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
      * @param lateSymbols The late-bound symbols of the parent.
      * @param decl The member to bind.
      */
-    function lateBindMember(parent: Symbol, earlySymbols: SymbolTable | undefined, lateSymbols: UnderscoreEscapedMap<TransientSymbol>, decl: LateBoundDeclaration | LateBoundBinaryExpressionDeclaration) {
+    function lateBindMember(parent: Symbol, earlySymbols: SymbolTable | undefined, lateSymbols: Map<__String, TransientSymbol>, decl: LateBoundDeclaration | LateBoundBinaryExpressionDeclaration) {
         Debug.assert(!!decl.symbol, "The member is expected to have a symbol.");
         const links = getNodeLinks(decl);
         if (!links.resolvedSymbol) {
@@ -12398,7 +12397,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         return links.resolvedSymbol;
     }
 
-    function getResolvedMembersOrExportsOfSymbol(symbol: Symbol, resolutionKind: MembersOrExportsResolutionKind): UnderscoreEscapedMap<Symbol> {
+    function getResolvedMembersOrExportsOfSymbol(symbol: Symbol, resolutionKind: MembersOrExportsResolutionKind): Map<__String, Symbol> {
         const links = getSymbolLinks(symbol);
         if (!links[resolutionKind]) {
             const isStatic = resolutionKind === MembersOrExportsResolutionKind.resolvedExports;
@@ -12412,7 +12411,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             links[resolutionKind] = earlySymbols || emptySymbols;
 
             // fill in any as-yet-unresolved late-bound members.
-            const lateSymbols = createSymbolTable() as UnderscoreEscapedMap<TransientSymbol>;
+            const lateSymbols = createSymbolTable() as Map<__String, TransientSymbol>;
             for (const decl of symbol.declarations || emptyArray) {
                 const members = getMembersOfDeclaration(decl);
                 if (members) {
@@ -13013,7 +13012,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         if (symbol.exports) {
             members = getExportsOfSymbol(symbol);
             if (symbol === globalThisSymbol) {
-                const varsOnly = new Map<string, Symbol>() as SymbolTable;
+                const varsOnly = new Map<__String, Symbol>();
                 members.forEach(p => {
                     if (!(p.flags & SymbolFlags.BlockScoped) && !(p.flags & SymbolFlags.ValueModule && p.declarations?.length && every(p.declarations, isAmbientModule))) {
                         varsOnly.set(p.escapedName, p);
@@ -23426,7 +23425,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
 
     function getPropertiesOfContext(context: WideningContext): Symbol[] {
         if (!context.resolvedProperties) {
-            const names = new Map<string, Symbol>() as UnderscoreEscapedMap<Symbol>;
+            const names = new Map<__String, Symbol>();
             for (const t of getSiblingsOfContext(context)) {
                 if (isObjectLiteralType(t) && !(getObjectFlags(t) & ObjectFlags.ContainsSpread)) {
                     for (const prop of getPropertiesOfType(t)) {
@@ -37912,7 +37911,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             }
         }
 
-        function addName(names: UnderscoreEscapedMap<DeclarationMeaning>, location: Node, name: __String, meaning: DeclarationMeaning) {
+        function addName(names: Map<__String, DeclarationMeaning>, location: Node, name: __String, meaning: DeclarationMeaning) {
             const prev = names.get(name);
             if (prev) {
                 // For private identifiers, do not allow mixing of static and instance members with the same name
diff --git a/src/compiler/core.ts b/src/compiler/core.ts
index e24f79ef628..c16ae51c3aa 100644
--- a/src/compiler/core.ts
+++ b/src/compiler/core.ts
@@ -1625,10 +1625,6 @@ export interface MultiMap<K, V> extends Map<K, V[]> {
     remove(key: K, value: V): void;
 }
 
-/** @internal */
-export function createMultiMap<K, V>(): MultiMap<K, V>;
-/** @internal */
-export function createMultiMap<V>(): MultiMap<string, V>;
 /** @internal */
 export function createMultiMap<K, V>(): MultiMap<K, V> {
     const map = new Map<K, V[]>() as MultiMap<K, V>;
diff --git a/src/compiler/resolutionCache.ts b/src/compiler/resolutionCache.ts
index 6784dad515f..0f29b75d31b 100644
--- a/src/compiler/resolutionCache.ts
+++ b/src/compiler/resolutionCache.ts
@@ -263,7 +263,7 @@ export function createResolutionCache(resolutionHost: ResolutionCacheHost, rootD
     let filesWithChangedSetOfUnresolvedImports: Path[] | undefined;
     let filesWithInvalidatedResolutions: Set<Path> | undefined;
     let filesWithInvalidatedNonRelativeUnresolvedImports: ReadonlyMap<Path, readonly string[]> | undefined;
-    const nonRelativeExternalModuleResolutions = createMultiMap<ResolutionWithFailedLookupLocations>();
+    const nonRelativeExternalModuleResolutions = createMultiMap<string, ResolutionWithFailedLookupLocations>();
 
     const resolutionsWithFailedLookups = new Set<ResolutionWithFailedLookupLocations>();
     const resolutionsWithOnlyAffectingLocations = new Set<ResolutionWithFailedLookupLocations>();
diff --git a/src/compiler/sys.ts b/src/compiler/sys.ts
index 23810846bfa..df9221e20ab 100644
--- a/src/compiler/sys.ts
+++ b/src/compiler/sys.ts
@@ -380,7 +380,7 @@ function createDynamicPriorityPollingWatchFile(host: {
 
 function createUseFsEventsOnParentDirectoryWatchFile(fsWatch: FsWatch, useCaseSensitiveFileNames: boolean): HostWatchFile {
     // One file can have multiple watchers
-    const fileWatcherCallbacks = createMultiMap<FileWatcherCallback>();
+    const fileWatcherCallbacks = createMultiMap<string, FileWatcherCallback>();
     const dirWatchers = new Map<string, DirectoryWatcher>();
     const toCanonicalName = createGetCanonicalFileName(useCaseSensitiveFileNames);
     return nonPollingWatchFile;
diff --git a/src/compiler/transformers/ts.ts b/src/compiler/transformers/ts.ts
index c92fb214ba6..1a2d982e410 100644
--- a/src/compiler/transformers/ts.ts
+++ b/src/compiler/transformers/ts.ts
@@ -186,7 +186,6 @@ import {
     TextRange,
     TransformationContext,
     TransformFlags,
-    UnderscoreEscapedMap,
     VariableDeclaration,
     VariableStatement,
     visitEachChild,
@@ -260,7 +259,7 @@ export function transformTypeScript(context: TransformationContext) {
     let currentNamespace: ModuleDeclaration;
     let currentNamespaceContainerName: Identifier;
     let currentLexicalScope: SourceFile | Block | ModuleBlock | CaseBlock;
-    let currentScopeFirstDeclarationsOfName: UnderscoreEscapedMap<Node> | undefined;
+    let currentScopeFirstDeclarationsOfName: Map<__String, Node> | undefined;
     let currentClassHasParameterProperties: boolean | undefined;
 
     /**
diff --git a/src/compiler/transformers/utilities.ts b/src/compiler/transformers/utilities.ts
index e6fd5c2346b..9650ae1a4a8 100644
--- a/src/compiler/transformers/utilities.ts
+++ b/src/compiler/transformers/utilities.ts
@@ -1,4 +1,5 @@
 import {
+    __String,
     AccessorDeclaration,
     AllDecorators,
     append,
@@ -81,7 +82,6 @@ import {
     SuperCall,
     SyntaxKind,
     TransformationContext,
-    UnderscoreEscapedMap,
     VariableDeclaration,
     VariableStatement,
 } from "../_namespaces/ts";
@@ -160,7 +160,7 @@ export function getImportNeedsImportDefaultHelper(node: ImportDeclaration): bool
 /** @internal */
 export function collectExternalModuleInfo(context: TransformationContext, sourceFile: SourceFile, resolver: EmitResolver, compilerOptions: CompilerOptions): ExternalModuleInfo {
     const externalImports: (ImportDeclaration | ImportEqualsDeclaration | ExportDeclaration)[] = [];
-    const exportSpecifiers = createMultiMap<ExportSpecifier>();
+    const exportSpecifiers = createMultiMap<string, ExportSpecifier>();
     const exportedBindings: Identifier[][] = [];
     const uniqueExports = new Map<string, boolean>();
     let exportedNames: Identifier[] | undefined;
@@ -652,7 +652,7 @@ export interface PrivateEnvironment<TData, TEntry> {
     /**
      * A mapping of private names to information needed for transformation.
      */
-    identifiers?: UnderscoreEscapedMap<TEntry>;
+    identifiers?: Map<__String, TEntry>;
 
     /**
      * A mapping of generated private names to information needed for transformation.
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index 7bae07044f7..1cb2ebfac22 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -5811,7 +5811,7 @@ export interface SymbolLinks {
     deferralParent?: Type;                      // Source union/intersection of a deferred type
     cjsExportMerged?: Symbol;                   // Version of the symbol with all non export= exports merged with the export= target
     typeOnlyDeclaration?: TypeOnlyAliasDeclaration | false; // First resolved alias declaration that makes the symbol only usable in type constructs
-    typeOnlyExportStarMap?: UnderscoreEscapedMap<ExportDeclaration & { readonly isTypeOnly: true }>; // Set on a module symbol when some of its exports were resolved through a 'export type * from "mod"' declaration
+    typeOnlyExportStarMap?: Map<__String, ExportDeclaration & { readonly isTypeOnly: true }>; // Set on a module symbol when some of its exports were resolved through a 'export type * from "mod"' declaration
     typeOnlyExportStarName?: __String;          // Set to the name of the symbol re-exported by an 'export type *' declaration, when different from the symbol name
     isConstructorDeclaredProperty?: boolean;    // Property declared through 'this.x = ...' assignment in constructor
     tupleLabelDeclaration?: NamedTupleMember | ParameterDeclaration; // Declaration associated with the tuple's label
@@ -5917,16 +5917,14 @@ export const enum InternalSymbolName {
  */
 export type __String = (string & { __escapedIdentifier: void }) | (void & { __escapedIdentifier: void }) | InternalSymbolName;
 
-/** ReadonlyMap where keys are `__String`s. */
-export interface ReadonlyUnderscoreEscapedMap<T> extends ReadonlyMap<__String, T> {
-}
+/** @deprecated Use ReadonlyMap<__String, T> instead. */
+export type ReadonlyUnderscoreEscapedMap<T> = ReadonlyMap<__String, T>;
 
-/** Map where keys are `__String`s. */
-export interface UnderscoreEscapedMap<T> extends Map<__String, T> {
-}
+/** @deprecated Use Map<__String, T> instead. */
+export type UnderscoreEscapedMap<T> = Map<__String, T>;
 
 /** SymbolTable based on ES6 Map interface. */
-export type SymbolTable = UnderscoreEscapedMap<Symbol>;
+export type SymbolTable = Map<__String, Symbol>;
 
 /**
  * Used to track a `declare module "foo*"`-like declaration.
diff --git a/src/harness/fourslashImpl.ts b/src/harness/fourslashImpl.ts
index 755f5c648b6..2efd53af5b3 100644
--- a/src/harness/fourslashImpl.ts
+++ b/src/harness/fourslashImpl.ts
@@ -2692,7 +2692,7 @@ export class TestState {
 
     public rangesByText(): Map<string, Range[]> {
         if (this.testData.rangesByText) return this.testData.rangesByText;
-        const result = ts.createMultiMap<Range>();
+        const result = ts.createMultiMap<string, Range>();
         this.testData.rangesByText = result;
         for (const range of this.getRanges()) {
             const text = this.rangeText(range);
diff --git a/src/services/codeFixProvider.ts b/src/services/codeFixProvider.ts
index de923d72424..bcdda2349fd 100644
--- a/src/services/codeFixProvider.ts
+++ b/src/services/codeFixProvider.ts
@@ -25,7 +25,7 @@ import {
     textChanges,
 } from "./_namespaces/ts";
 
-const errorCodeToFixes = createMultiMap<CodeFixRegistration>();
+const errorCodeToFixes = createMultiMap<string, CodeFixRegistration>();
 const fixIdToRegistration = new Map<string, CodeFixRegistration>();
 
 /** @internal */
diff --git a/src/services/codefixes/convertToAsyncFunction.ts b/src/services/codefixes/convertToAsyncFunction.ts
index e6851157938..1f62bd26e19 100644
--- a/src/services/codefixes/convertToAsyncFunction.ts
+++ b/src/services/codefixes/convertToAsyncFunction.ts
@@ -285,7 +285,7 @@ function isPromiseTypedExpression(node: Node, checker: TypeChecker): node is Exp
 */
 function renameCollidingVarNames(nodeToRename: FunctionLikeDeclaration, checker: TypeChecker, synthNamesMap: Map<string, SynthIdentifier>): FunctionLikeDeclaration {
     const identsToRenameMap = new Map<string, Identifier>(); // key is the symbol id
-    const collidingSymbolMap = createMultiMap<Symbol>();
+    const collidingSymbolMap = createMultiMap<string, Symbol>();
     forEachChild(nodeToRename, function visit(node: Node) {
         if (!isIdentifier(node)) {
             forEachChild(node, visit);
diff --git a/src/services/codefixes/convertToEsModule.ts b/src/services/codefixes/convertToEsModule.ts
index 7a4dbc97eea..2643d4d1ad3 100644
--- a/src/services/codefixes/convertToEsModule.ts
+++ b/src/services/codefixes/convertToEsModule.ts
@@ -594,7 +594,7 @@ interface Identifiers {
 
 type FreeIdentifiers = ReadonlyMap<string, readonly Identifier[]>;
 function collectFreeIdentifiers(file: SourceFile): FreeIdentifiers {
-    const map = createMultiMap<Identifier>();
+    const map = createMultiMap<string, Identifier>();
     forEachFreeIdentifier(file, id => map.add(id.text, id));
     return map;
 }
diff --git a/src/services/codefixes/importFixes.ts b/src/services/codefixes/importFixes.ts
index 64389726ebc..fe82e145ed8 100644
--- a/src/services/codefixes/importFixes.ts
+++ b/src/services/codefixes/importFixes.ts
@@ -1148,7 +1148,7 @@ function getExportInfos(
 ): ReadonlyMap<string, readonly SymbolExportInfo[]> {
     // For each original symbol, keep all re-exports of that symbol together so we can call `getCodeActionsForImport` on the whole group at once.
     // Maps symbol id to info for modules providing that symbol (original export + re-exports).
-    const originalSymbolToExportInfos = createMultiMap<SymbolExportInfo>();
+    const originalSymbolToExportInfos = createMultiMap<string, SymbolExportInfo>();
     const packageJsonFilter = createPackageJsonImportFilter(fromFile, preferences, host);
     const moduleSpecifierCache = host.getModuleSpecifierCache?.();
     const getModuleSpecifierResolutionHost = memoizeOne((isFromPackageJson: boolean) => {
diff --git a/src/services/codefixes/inferFromUsage.ts b/src/services/codefixes/inferFromUsage.ts
index e49ead2f36f..d76babcb778 100644
--- a/src/services/codefixes/inferFromUsage.ts
+++ b/src/services/codefixes/inferFromUsage.ts
@@ -92,13 +92,11 @@ import {
     SyntaxKind,
     textChanges,
     Token,
-    TransientSymbol,
     tryCast,
     Type,
     TypeFlags,
     TypeNode,
     TypeReference,
-    UnderscoreEscapedMap,
     UnionOrIntersectionType,
     UnionReduction,
     UserPreferences,
@@ -581,7 +579,7 @@ function inferTypeFromReferences(program: Program, references: readonly Identifi
         isNumberOrString: boolean | undefined;
 
         candidateTypes: Type[] | undefined;
-        properties: UnderscoreEscapedMap<Usage> | undefined;
+        properties: Map<__String, Usage> | undefined;
         calls: CallUsage[] | undefined;
         constructs: CallUsage[] | undefined;
         numberIndex: Usage | undefined;
@@ -1024,10 +1022,10 @@ function inferTypeFromReferences(program: Program, references: readonly Identifi
         const numberIndices = [];
         let stringIndexReadonly = false;
         let numberIndexReadonly = false;
-        const props = createMultiMap<Type>();
+        const props = createMultiMap<__String, Type>();
         for (const anon of anons) {
             for (const p of checker.getPropertiesOfType(anon)) {
-                props.add(p.name, p.valueDeclaration ? checker.getTypeOfSymbolAtLocation(p, p.valueDeclaration) : checker.getAnyType());
+                props.add(p.escapedName, p.valueDeclaration ? checker.getTypeOfSymbolAtLocation(p, p.valueDeclaration) : checker.getAnyType());
             }
             calls.push(...checker.getSignaturesOfType(anon, SignatureKind.Call));
             constructs.push(...checker.getSignaturesOfType(anon, SignatureKind.Construct));
@@ -1044,7 +1042,7 @@ function inferTypeFromReferences(program: Program, references: readonly Identifi
         }
         const members = mapEntries(props, (name, types) => {
             const isOptional = types.length < anons.length ? SymbolFlags.Optional : 0;
-            const s = checker.createSymbol(SymbolFlags.Property | isOptional, name as __String);
+            const s = checker.createSymbol(SymbolFlags.Property | isOptional, name);
             s.links.type = checker.getUnionType(types);
             return [name, s];
         });
@@ -1053,7 +1051,7 @@ function inferTypeFromReferences(program: Program, references: readonly Identifi
         if (numberIndices.length) indexInfos.push(checker.createIndexInfo(checker.getNumberType(), checker.getUnionType(numberIndices), numberIndexReadonly));
         return checker.createAnonymousType(
             anons[0].symbol,
-            members as UnderscoreEscapedMap<TransientSymbol>,
+            members,
             calls,
             constructs,
             indexInfos);
diff --git a/src/services/services.ts b/src/services/services.ts
index f5bba46bdbc..953c29c3ec8 100644
--- a/src/services/services.ts
+++ b/src/services/services.ts
@@ -309,7 +309,6 @@ import {
     TypePredicate,
     TypeReference,
     typeToDisplayParts,
-    UnderscoreEscapedMap,
     UnionOrIntersectionType,
     UnionType,
     updateSourceFile,
@@ -1030,7 +1029,7 @@ class SourceFileObject extends NodeObject implements SourceFile {
     public languageVersion!: ScriptTarget;
     public languageVariant!: LanguageVariant;
     public identifiers!: Map<string, string>;
-    public nameTable: UnderscoreEscapedMap<number> | undefined;
+    public nameTable: Map<__String, number> | undefined;
     public resolvedModules: ModeAwareCache<ResolvedModuleWithFailedLookupLocations> | undefined;
     public resolvedTypeReferenceDirectiveNames!: ModeAwareCache<ResolvedTypeReferenceDirectiveWithFailedLookupLocations>;
     public imports!: readonly StringLiteralLike[];
@@ -1090,7 +1089,7 @@ class SourceFileObject extends NodeObject implements SourceFile {
     }
 
     private computeNamedDeclarations(): Map<string, Declaration[]> {
-        const result = createMultiMap<Declaration>();
+        const result = createMultiMap<string, Declaration>();
 
         this.forEachChild(visit);
 
@@ -3082,7 +3081,7 @@ export function createLanguageService(
  *
  * @internal
  */
-export function getNameTable(sourceFile: SourceFile): UnderscoreEscapedMap<number> {
+export function getNameTable(sourceFile: SourceFile): Map<__String, number> {
     if (!sourceFile.nameTable) {
         initializeNameTable(sourceFile);
     }
diff --git a/src/services/types.ts b/src/services/types.ts
index d0ed926108d..6af97fa7ef2 100644
--- a/src/services/types.ts
+++ b/src/services/types.ts
@@ -159,7 +159,7 @@ declare module "../compiler/types" {
     export interface SourceFile {
         /** @internal */ version: string;
         /** @internal */ scriptSnapshot: IScriptSnapshot | undefined;
-        /** @internal */ nameTable: UnderscoreEscapedMap<number> | undefined;
+        /** @internal */ nameTable: Map<__String, number> | undefined;
 
         /** @internal */ getNamedDeclarations(): Map<string, readonly Declaration[]>;
 
diff --git a/src/testRunner/unittests/tsserver/cachingFileSystemInformation.ts b/src/testRunner/unittests/tsserver/cachingFileSystemInformation.ts
index 12e650e4d84..15aec588ed2 100644
--- a/src/testRunner/unittests/tsserver/cachingFileSystemInformation.ts
+++ b/src/testRunner/unittests/tsserver/cachingFileSystemInformation.ts
@@ -43,7 +43,7 @@ describe("unittests:: tsserver:: CachingFileSystemInformation:: tsserverProjectS
         return logCacheAndClear;
 
         function setCallsTrackingWithSingleArgFn(prop: CalledMapsWithSingleArg) {
-            const calledMap = ts.createMultiMap<true>();
+            const calledMap = ts.createMultiMap<string, true>();
             const cb = (host as any)[prop].bind(host);
             (host as any)[prop] = (f: string) => {
                 calledMap.add(f, /*value*/ true);
@@ -53,7 +53,7 @@ describe("unittests:: tsserver:: CachingFileSystemInformation:: tsserverProjectS
         }
 
         function setCallsTrackingWithFiveArgFn<U, V, W, X>(prop: CalledMapsWithFiveArgs) {
-            const calledMap = ts.createMultiMap<[U, V, W, X]>();
+            const calledMap = ts.createMultiMap<string, [U, V, W, X]>();
             const cb = (host as any)[prop].bind(host);
             (host as any)[prop] = (f: string, arg1?: U, arg2?: V, arg3?: W, arg4?: X) => {
                 calledMap.add(f, [arg1!, arg2!, arg3!, arg4!]); // TODO: GH#18217
diff --git a/tests/baselines/reference/api/tsserverlibrary.d.ts b/tests/baselines/reference/api/tsserverlibrary.d.ts
index 0a8127b2a19..deca7c43b4b 100644
--- a/tests/baselines/reference/api/tsserverlibrary.d.ts
+++ b/tests/baselines/reference/api/tsserverlibrary.d.ts
@@ -6636,14 +6636,12 @@ declare namespace ts {
     }) | (void & {
         __escapedIdentifier: void;
     }) | InternalSymbolName;
-    /** ReadonlyMap where keys are `__String`s. */
-    interface ReadonlyUnderscoreEscapedMap<T> extends ReadonlyMap<__String, T> {
-    }
-    /** Map where keys are `__String`s. */
-    interface UnderscoreEscapedMap<T> extends Map<__String, T> {
-    }
+    /** @deprecated Use ReadonlyMap<__String, T> instead. */
+    type ReadonlyUnderscoreEscapedMap<T> = ReadonlyMap<__String, T>;
+    /** @deprecated Use Map<__String, T> instead. */
+    type UnderscoreEscapedMap<T> = Map<__String, T>;
     /** SymbolTable based on ES6 Map interface. */
-    type SymbolTable = UnderscoreEscapedMap<Symbol>;
+    type SymbolTable = Map<__String, Symbol>;
     enum TypeFlags {
         Any = 1,
         Unknown = 2,
diff --git a/tests/baselines/reference/api/typescript.d.ts b/tests/baselines/reference/api/typescript.d.ts
index 920d6e74840..b7a1a455832 100644
--- a/tests/baselines/reference/api/typescript.d.ts
+++ b/tests/baselines/reference/api/typescript.d.ts
@@ -2661,14 +2661,12 @@ declare namespace ts {
     }) | (void & {
         __escapedIdentifier: void;
     }) | InternalSymbolName;
-    /** ReadonlyMap where keys are `__String`s. */
-    interface ReadonlyUnderscoreEscapedMap<T> extends ReadonlyMap<__String, T> {
-    }
-    /** Map where keys are `__String`s. */
-    interface UnderscoreEscapedMap<T> extends Map<__String, T> {
-    }
+    /** @deprecated Use ReadonlyMap<__String, T> instead. */
+    type ReadonlyUnderscoreEscapedMap<T> = ReadonlyMap<__String, T>;
+    /** @deprecated Use Map<__String, T> instead. */
+    type UnderscoreEscapedMap<T> = Map<__String, T>;
     /** SymbolTable based on ES6 Map interface. */
-    type SymbolTable = UnderscoreEscapedMap<Symbol>;
+    type SymbolTable = Map<__String, Symbol>;
     enum TypeFlags {
         Any = 1,
         Unknown = 2,