diff --git a/src/dev/file.ts b/src/dev/file.ts
index b4283de3dbe4..5dc66016e1e5 100644
--- a/src/dev/file.ts
+++ b/src/dev/file.ts
@@ -48,6 +48,10 @@ export class File {
     return this.ext === '.ts' || this.ext === '.tsx';
   }
 
+  public isTypescriptAmbient() {
+    return this.path.endsWith('.d.ts');
+  }
+
   public isSass() {
     return this.ext === '.sass' || this.ext === '.scss';
   }
diff --git a/src/dev/typescript/get_ts_project_for_absolute_path.ts b/src/dev/typescript/get_ts_project_for_absolute_path.ts
index 409d18bed6f5..843743fd7a3b 100644
--- a/src/dev/typescript/get_ts_project_for_absolute_path.ts
+++ b/src/dev/typescript/get_ts_project_for_absolute_path.ts
@@ -17,9 +17,10 @@
  * under the License.
  */
 
-import { relative } from 'path';
+import { relative, resolve } from 'path';
 
 import { REPO_ROOT } from '../constants';
+import { File } from '../file';
 import { PROJECTS } from './projects';
 
 /**
@@ -33,6 +34,7 @@ import { PROJECTS } from './projects';
  */
 export function getTsProjectForAbsolutePath(path: string) {
   const relPath = relative(REPO_ROOT, path);
+  const file = new File(resolve(REPO_ROOT, path));
   const projects = PROJECTS.filter(p => p.isAbsolutePathSelected(path));
 
   if (!projects.length) {
@@ -41,7 +43,7 @@ export function getTsProjectForAbsolutePath(path: string) {
     );
   }
 
-  if (projects.length !== 1) {
+  if (projects.length !== 1 && !file.isTypescriptAmbient()) {
     const configPaths = projects.map(p => `"${relative(REPO_ROOT, p.tsConfigPath)}"`);
 
     const pathsMsg = `${configPaths.slice(0, -1).join(', ')} or ${
diff --git a/src/dev/typescript/run_check_ts_projects_cli.ts b/src/dev/typescript/run_check_ts_projects_cli.ts
index d9c1259882c5..d4a4b5dee5fa 100644
--- a/src/dev/typescript/run_check_ts_projects_cli.ts
+++ b/src/dev/typescript/run_check_ts_projects_cli.ts
@@ -55,7 +55,7 @@ export async function runCheckTsProjectsCli() {
         if (projects.length === 0) {
           isNotInTsProject.push(file);
         }
-        if (projects.length > 1) {
+        if (projects.length > 1 && !file.isTypescriptAmbient()) {
           isInMultipleTsProjects.push(file);
         }
       }