diff --git a/src/diagnosticMessages.json b/src/diagnosticMessages.json
index 5c9a03e6f2..c77e0e9519 100644
--- a/src/diagnosticMessages.json
+++ b/src/diagnosticMessages.json
@@ -114,6 +114,7 @@
   "A definite assignment assertion '!' is not permitted in this context.": 1255,
   "A class may only extend another class.": 1311,
   "A parameter property cannot be declared using a rest parameter.": 1317,
+  "A default export can only be used in a module.": 1319,
   "An identifier or keyword cannot immediately follow a numeric literal.": 1351,
 
   "Duplicate identifier '{0}'.": 2300,
diff --git a/src/parser.ts b/src/parser.ts
index b9dc2fc7b3..08bf51e1dc 100644
--- a/src/parser.ts
+++ b/src/parser.ts
@@ -2483,8 +2483,16 @@ export class Parser extends DiagnosticEmitter {
         );
         while (!tn.skip(Token.CLOSEBRACE)) {
           let member = this.parseTopLevelStatement(tn, declaration);
-          if (member) members.push(member);
-          else {
+          if (member) {
+            if (member.kind == NodeKind.EXPORT) {
+              this.error(
+                DiagnosticCode.A_default_export_can_only_be_used_in_a_module,
+                member.range,
+              );
+              return null;
+            }
+            members.push(member);
+          } else {
             this.skipStatement(tn);
             if (tn.skip(Token.ENDOFFILE)) {
               this.error(
diff --git a/tests/parser/export-default-in-namespace.ts b/tests/parser/export-default-in-namespace.ts
new file mode 100644
index 0000000000..a9f1432bb6
--- /dev/null
+++ b/tests/parser/export-default-in-namespace.ts
@@ -0,0 +1,3 @@
+namespace Foo {
+  export default bar;
+}
diff --git a/tests/parser/export-default-in-namespace.ts.fixture.ts b/tests/parser/export-default-in-namespace.ts.fixture.ts
new file mode 100644
index 0000000000..5f0dfe42e8
--- /dev/null
+++ b/tests/parser/export-default-in-namespace.ts.fixture.ts
@@ -0,0 +1 @@
+// ERROR 1319: "A default export can only be used in a module." in export-default-in-namespace.ts(2,3+18)