diff --git a/src/compiler/program.ts b/src/compiler/program.ts
index 2455270330..dfc1c397eb 100644
--- a/src/compiler/program.ts
+++ b/src/compiler/program.ts
@@ -1577,6 +1577,7 @@ namespace ts {
                 newSourceFile.originalFileName = oldSourceFile.originalFileName;
                 newSourceFile.resolvedPath = oldSourceFile.resolvedPath;
                 newSourceFile.fileName = oldSourceFile.fileName;
+                newSourceFile.impliedNodeFormat = oldSourceFile.impliedNodeFormat;
 
                 const packageName = oldProgram.sourceFileToPackageName.get(oldSourceFile.path);
                 if (packageName !== undefined) {
diff --git a/src/harness/fourslashImpl.ts b/src/harness/fourslashImpl.ts
index 0e8b1825d9..a086eff4fc 100644
--- a/src/harness/fourslashImpl.ts
+++ b/src/harness/fourslashImpl.ts
@@ -637,7 +637,8 @@ namespace FourSlash {
             ts.forEachKey(this.inputFiles, fileName => {
                 if (!ts.isAnySupportedFileExtension(fileName)
                     || Harness.getConfigNameFromFileName(fileName)
-                    || !ts.getAllowJSCompilerOption(this.getProgram().getCompilerOptions()) && !ts.resolutionExtensionIsTSOrJson(ts.extensionFromPath(fileName))
+                    // Can't get a Program in Server tests
+                    || this.testType !== FourSlashTestType.Server && !ts.getAllowJSCompilerOption(this.getProgram().getCompilerOptions()) && !ts.resolutionExtensionIsTSOrJson(ts.extensionFromPath(fileName))
                     || ts.getBaseFileName(fileName) === "package.json") return;
                 const errors = this.getDiagnostics(fileName).filter(e => e.category !== ts.DiagnosticCategory.Suggestion);
                 if (errors.length) {
diff --git a/tests/cases/fourslash/server/impliedNodeFormat.ts b/tests/cases/fourslash/server/impliedNodeFormat.ts
new file mode 100644
index 0000000000..d7faa92d3b
--- /dev/null
+++ b/tests/cases/fourslash/server/impliedNodeFormat.ts
@@ -0,0 +1,20 @@
+/// <reference path="../fourslash.ts" />
+
+// @Filename: /tsconfig.json
+//// { "compilerOptions": { "module": "nodenext" } }
+
+// @Filename: /package.json
+//// { "name": "foo", "type": "module", "exports": { ".": "./main.js" } }
+
+// @Filename: /main.ts
+//// export {};
+
+// @Filename: /index.ts
+//// import {} from "foo";
+
+goTo.file("/index.ts");
+verify.noErrors();
+
+edit.paste(`\n"${"a".repeat(256)}";`);
+
+verify.noErrors();