diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 0bc1cd61fcf..b2a0629cc71 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -110,6 +110,7 @@ import {
     createGetCanonicalFileName,
     createGetSymbolWalker,
     createModeAwareCacheKey,
+    createMultiMap,
     createPrinterWithDefaults,
     createPrinterWithRemoveComments,
     createPrinterWithRemoveCommentsNeverAsciiEscape,
@@ -117,7 +118,6 @@ import {
     createPropertyNameNodeForIdentifierOrLiteral,
     createSymbolTable,
     createTextWriter,
-    createUnderscoreEscapedMultiMap,
     Debug,
     Declaration,
     DeclarationName,
@@ -7187,7 +7187,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                 }
                 const mayHaveNameCollisions = !(context.flags & NodeBuilderFlags.UseFullyQualifiedType);
                 /** Map from type reference identifier text to [type, index in `result` where the type node is] */
-                const seenNames = mayHaveNameCollisions ? createUnderscoreEscapedMultiMap<[Type, number]>() : undefined;
+                const seenNames = mayHaveNameCollisions ? createMultiMap<__String, [Type, number]>() : undefined;
                 const result: TypeNode[] = [];
                 let i = 0;
                 for (const type of types) {
diff --git a/src/compiler/core.ts b/src/compiler/core.ts
index 2dc7f533c76..e24f79ef628 100644
--- a/src/compiler/core.ts
+++ b/src/compiler/core.ts
@@ -12,7 +12,6 @@ import {
     SortedArray,
     SortedReadonlyArray,
     TextSpan,
-    UnderscoreEscapedMap,
 } from "./_namespaces/ts";
 
 
@@ -1657,26 +1656,6 @@ function multiMapRemove<K, V>(this: MultiMap<K, V>, key: K, value: V) {
     }
 }
 
-/** @internal */
-export interface UnderscoreEscapedMultiMap<T> extends UnderscoreEscapedMap<T[]> {
-    /**
-     * Adds the value to an array of values associated with the key, and returns the array.
-     * Creates the array if it does not already exist.
-     */
-    add(key: __String, value: T): T[];
-    /**
-     * Removes a value from an array of values associated with the key.
-     * Does not preserve the order of those values.
-     * Does nothing if `key` is not in `map`, or `value` is not in `map[key]`.
-     */
-    remove(key: __String, value: T): void;
-}
-
-/** @internal */
-export function createUnderscoreEscapedMultiMap<T>(): UnderscoreEscapedMultiMap<T> {
-    return createMultiMap() as UnderscoreEscapedMultiMap<T>;
-}
-
 /** @internal */
 export function createQueue<T>(items?: readonly T[]): Queue<T> {
     const elements: (T | undefined)[] = items?.slice() || [];