diff --git a/packages/language-server/src/plugins/typescript/TypeScriptPlugin.ts b/packages/language-server/src/plugins/typescript/TypeScriptPlugin.ts
index efc5132c7..14f3723af 100644
--- a/packages/language-server/src/plugins/typescript/TypeScriptPlugin.ts
+++ b/packages/language-server/src/plugins/typescript/TypeScriptPlugin.ts
@@ -455,7 +455,12 @@ export class TypeScriptPlugin
         for (const { fileName, changeType } of onWatchFileChangesParas) {
             const pathParts = fileName.split(/\/|\\/);
             const dirPathParts = pathParts.slice(0, pathParts.length - 1);
-            if (ignoredBuildDirectories.some((dir) => dirPathParts.includes(dir))) {
+            const declarationExtensions = [ts.Extension.Dcts, ts.Extension.Dts, ts.Extension.Dmts];
+            const canSafelyIgnore =
+                declarationExtensions.every((ext) => !fileName.endsWith(ext)) &&
+                ignoredBuildDirectories.some((dir) => dirPathParts.includes(dir));
+
+            if (canSafelyIgnore) {
                 continue;
             }
 
diff --git a/packages/language-server/test/plugins/typescript/TypescriptPlugin.test.ts b/packages/language-server/test/plugins/typescript/TypescriptPlugin.test.ts
index 1b2ae1ad5..c7ad1ba3c 100644
--- a/packages/language-server/test/plugins/typescript/TypescriptPlugin.test.ts
+++ b/packages/language-server/test/plugins/typescript/TypescriptPlugin.test.ts
@@ -940,6 +940,10 @@ function test(useNewTransformation: boolean) {
             }
         });
 
+        it('should add declaration file snapshot when added to known build directory', async () => {
+            await testForOnWatchedFileAdd(path.join('.svelte-kit', 'ambient.d.ts'), true);
+        });
+
         it('should update ts/js file after document change', async () => {
             const { snapshotManager, projectJsFile, plugin } =
                 await setupForOnWatchedFileUpdateOrDelete();