diff --git a/src/compiler/core.ts b/src/compiler/core.ts
index 06f8b24a4c6..2966582cb39 100644
--- a/src/compiler/core.ts
+++ b/src/compiler/core.ts
@@ -16,6 +16,10 @@ namespace ts {
         // Update: We also consider a path like `C:\foo.ts` "relative" because we do not search for it in `node_modules` or treat it as an ambient module.
         return pathIsRelative(moduleName) || isRootedDiskPath(moduleName);
     }
+
+    export function sortAndDeduplicateDiagnostics(diagnostics: ReadonlyArray<Diagnostic>): Diagnostic[] {
+        return sortAndDeduplicate(diagnostics, compareDiagnostics);
+    }
 }
 
 /* @internal */
@@ -1901,10 +1905,6 @@ namespace ts {
         return text1 ? Comparison.GreaterThan : Comparison.LessThan;
     }
 
-    export function sortAndDeduplicateDiagnostics(diagnostics: ReadonlyArray<Diagnostic>): Diagnostic[] {
-        return sortAndDeduplicate(diagnostics, compareDiagnostics);
-    }
-
     export function normalizeSlashes(path: string): string {
         return path.replace(/\\/g, "/");
     }
diff --git a/tests/baselines/reference/api/tsserverlibrary.d.ts b/tests/baselines/reference/api/tsserverlibrary.d.ts
index a2ded98383e..c1af8fc036f 100644
--- a/tests/baselines/reference/api/tsserverlibrary.d.ts
+++ b/tests/baselines/reference/api/tsserverlibrary.d.ts
@@ -2814,6 +2814,7 @@ declare namespace ts {
 }
 declare namespace ts {
     function isExternalModuleNameRelative(moduleName: string): boolean;
+    function sortAndDeduplicateDiagnostics(diagnostics: ReadonlyArray<Diagnostic>): Diagnostic[];
 }
 declare function setTimeout(handler: (...args: any[]) => void, timeout: number): any;
 declare function clearTimeout(handle: any): void;
diff --git a/tests/baselines/reference/api/typescript.d.ts b/tests/baselines/reference/api/typescript.d.ts
index 2cf666b1cf3..4f84f50e3bb 100644
--- a/tests/baselines/reference/api/typescript.d.ts
+++ b/tests/baselines/reference/api/typescript.d.ts
@@ -2814,6 +2814,7 @@ declare namespace ts {
 }
 declare namespace ts {
     function isExternalModuleNameRelative(moduleName: string): boolean;
+    function sortAndDeduplicateDiagnostics(diagnostics: ReadonlyArray<Diagnostic>): Diagnostic[];
 }
 declare function setTimeout(handler: (...args: any[]) => void, timeout: number): any;
 declare function clearTimeout(handle: any): void;