diff --git a/src/compiler/core.ts b/src/compiler/core.ts
index 1db21ae46f0..9daf31f7899 100644
--- a/src/compiler/core.ts
+++ b/src/compiler/core.ts
@@ -1710,7 +1710,7 @@ namespace ts {
         return moduleResolution;
     }
 
-    export function getStrictOptionValue(compilerOptions: CompilerOptions, flag: "noImplicitAny" | "noImplicitThis" | "strictNullChecks" | "strictFunctionTypes" | "alwaysStrict"): boolean {
+    export function getStrictOptionValue(compilerOptions: CompilerOptions, flag: StrictOptionName): boolean {
         return compilerOptions[flag] === undefined ? compilerOptions.strict : compilerOptions[flag];
     }
 
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index fb59c9eb881..8749d06b43d 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -3676,6 +3676,8 @@ namespace ts {
 
     export type CompilerOptionsValue = string | number | boolean | (string | number)[] | string[] | MapLike<string[]> | PluginImport[] | null | undefined;
 
+    export type StrictOptionName = "noImplicitAny" | "noImplicitThis" | "strictNullChecks" | "strictFunctionTypes" | "alwaysStrict";
+
     export interface CompilerOptions {
         /*@internal*/ all?: boolean;
         allowJs?: boolean;