diff --git a/packages/language-server/src/plugins/typescript/features/DiagnosticsProvider.ts b/packages/language-server/src/plugins/typescript/features/DiagnosticsProvider.ts
index f0334143d..4f7e7dfc2 100644
--- a/packages/language-server/src/plugins/typescript/features/DiagnosticsProvider.ts
+++ b/packages/language-server/src/plugins/typescript/features/DiagnosticsProvider.ts
@@ -15,6 +15,20 @@ export class DiagnosticsProviderImpl implements DiagnosticsProvider {
         document: Document,
         cancellationToken?: CancellationToken
     ): Promise<Diagnostic[]> {
+        if (
+            (document.getFilePath()?.includes('/node_modules/') ||
+                document.getFilePath()?.includes('\\node_modules\\')) &&
+            // Sapper convention: Put stuff inside node_modules below src
+            !(
+                document.getFilePath()?.includes('/src/node_modules/') ||
+                document.getFilePath()?.includes('\\src\\node_modules\\')
+            )
+        ) {
+            // Don't return diagnostics for files inside node_modules. These are considered read-only (cannot be changed)
+            // and in case of svelte-check they would pollute/skew the output
+            return [];
+        }
+
         const { lang, tsDoc } = await this.getLSAndTSDoc(document);
 
         if (
diff --git a/packages/language-server/src/plugins/typescript/module-loader.ts b/packages/language-server/src/plugins/typescript/module-loader.ts
index 2801d59f1..b023318b1 100644
--- a/packages/language-server/src/plugins/typescript/module-loader.ts
+++ b/packages/language-server/src/plugins/typescript/module-loader.ts
@@ -146,7 +146,8 @@ export function createSvelteModuleLoader(
 
         const resolvedSvelteModule: ts.ResolvedModuleFull = {
             extension: getExtensionFromScriptKind(snapshot && snapshot.scriptKind),
-            resolvedFileName
+            resolvedFileName,
+            isExternalLibraryImport: svelteResolvedModule.isExternalLibraryImport
         };
         return resolvedSvelteModule;
     }
diff --git a/packages/language-server/test/plugins/typescript/module-loader.test.ts b/packages/language-server/test/plugins/typescript/module-loader.test.ts
index 5f1cd5bed..51fe58f2c 100644
--- a/packages/language-server/test/plugins/typescript/module-loader.test.ts
+++ b/packages/language-server/test/plugins/typescript/module-loader.test.ts
@@ -114,7 +114,8 @@ describe('createSvelteModuleLoader', () => {
         assert.deepStrictEqual(result, [
             <ts.ResolvedModuleFull>{
                 extension: ts.Extension.Jsx,
-                resolvedFileName: 'filename.svelte'
+                resolvedFileName: 'filename.svelte',
+                isExternalLibraryImport: undefined
             }
         ]);
         assert.deepStrictEqual(lastCall(resolveStub).args, [
@@ -141,7 +142,8 @@ describe('createSvelteModuleLoader', () => {
         assert.deepStrictEqual(result, [
             <ts.ResolvedModuleFull>{
                 extension: ts.Extension.Jsx,
-                resolvedFileName: 'filename.svelte'
+                resolvedFileName: 'filename.svelte',
+                isExternalLibraryImport: undefined
             }
         ]);
         assert.deepStrictEqual(lastCall(resolveStub).args, [
diff --git a/packages/svelte-check/README.md b/packages/svelte-check/README.md
index caafd31ca..7fb518536 100644
--- a/packages/svelte-check/README.md
+++ b/packages/svelte-check/README.md
@@ -56,7 +56,7 @@ Usage:
 | `--output <human\|human-verbose\|machine>`                      |
 | `--watch`                                                       | Will not exit after one pass but keep watching files for changes and rerun diagnostics                                                                                                                                                                                                                           |
 | `--tsconfig <path>`                                             | Pass a path to a tsconfig or jsconfig file. The path can be relative to the workspace path or absolute. Doing this means that only files matched by the files/include/exclude pattern of the config file are diagnosed. It also means that errors from TypeScript and JavaScript files are reported.             |
-| `--ignore <path1,path2>`                                        | Files/folders to ignore - relative to workspace root, comma-separated, inside quotes. Example: `--ignore "dist,build"`. When used in conjunction with `--tsconfig`, this will only have effect on the files watched, not on the files that are diagnosed, which is then determined by the `tsconfig.json`  |
+| `--ignore <path1,path2>`                                        | Files/folders to ignore - relative to workspace root, comma-separated, inside quotes. Example: `--ignore "dist,build"`. When used in conjunction with `--tsconfig`, this will only have effect on the files watched, not on the files that are diagnosed, which is then determined by the `tsconfig.json`        |
 | `--fail-on-warnings`                                            | Will also exit with error code when there are warnings                                                                                                                                                                                                                                                           |
 | `--fail-on-hints`                                               | Will also exit with error code when there are hints                                                                                                                                                                                                                                                              |
 | `--compiler-warnings <code1:error\|ignore,code2:error\|ignore>` | A list of Svelte compiler warning codes. Each entry defines whether that warning should be ignored or treated as an error. Warnings are comma-separated, between warning code and error level is a colon; all inside quotes. Example: `--compiler-warnings "css-unused-selector:ignore,unused-export-let:error"` |