diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index cae9f2dac25..b01c145c24b 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -3352,8 +3352,6 @@ namespace ts {
                                 getObjectFlags(type) & ObjectFlags.Anonymous &&
                                 type.symbol && type.symbol.flags & SymbolFlags.Class;
                             if (isConstructorObject) {
-                                // TODO: something needs to issue accessibility errors (here, I think)
-                                // before writing a literal type that flattens base types, check that the base types are accessible
                                 writeLiteralType(type, flags);
                             }
                             else {
@@ -3479,10 +3477,13 @@ namespace ts {
                     buildIndexSignatureDisplay(resolved.stringIndexInfo, writer, IndexKind.String, enclosingDeclaration, globalFlags, symbolStack);
                     buildIndexSignatureDisplay(resolved.numberIndexInfo, writer, IndexKind.Number, enclosingDeclaration, globalFlags, symbolStack);
                     for (const p of resolved.properties) {
-                        if (globalFlags & TypeFormatFlags.WriteClassExpressionAsTypeLiteral &&
-                            (p.name === "prototype" ||
-                             getDeclarationModifierFlagsFromSymbol(p) & (ModifierFlags.Private | ModifierFlags.Protected))) {
-                            continue;
+                        if (globalFlags & TypeFormatFlags.WriteClassExpressionAsTypeLiteral) {
+                            if (p.flags & SymbolFlags.Prototype) {
+                                continue;
+                            }
+                            if (getDeclarationModifierFlagsFromSymbol(p) & (ModifierFlags.Private | ModifierFlags.Protected)) {
+                                writer.reportPrivateInBaseOfClassExpression(p.name);
+                            }
                         }
                         const t = getTypeOfSymbol(p);
                         if (p.flags & (SymbolFlags.Function | SymbolFlags.Method) && !getPropertiesOfObjectType(t).length) {
diff --git a/src/compiler/declarationEmitter.ts b/src/compiler/declarationEmitter.ts
index 89358872a0f..3cc85aaa24b 100644
--- a/src/compiler/declarationEmitter.ts
+++ b/src/compiler/declarationEmitter.ts
@@ -190,7 +190,7 @@ namespace ts {
             const writer = <EmitTextWriterWithSymbolWriter>createTextWriter(newLine);
             writer.trackSymbol = trackSymbol;
             writer.reportInaccessibleThisError = reportInaccessibleThisError;
-            writer.reportIllegalExtends = reportIllegalExtends;
+            writer.reportPrivateInBaseOfClassExpression = reportPrivateInBaseOfClassExpression;
             writer.writeKeyword = writer.write;
             writer.writeOperator = writer.write;
             writer.writePunctuation = writer.write;
@@ -314,11 +314,11 @@ namespace ts {
             recordTypeReferenceDirectivesIfNecessary(resolver.getTypeReferenceDirectivesForSymbol(symbol, meaning));
         }
 
-        function reportIllegalExtends() {
+        function reportPrivateInBaseOfClassExpression(propertyName: string) {
             if (errorNameNode) {
                 reportedDeclarationError = true;
-                emitterDiagnostics.add(createDiagnosticForNode(errorNameNode, Diagnostics.extends_clause_of_exported_class_0_refers_to_a_type_whose_name_cannot_be_referenced,
-                    declarationNameToString(errorNameNode)));
+                emitterDiagnostics.add(
+                    createDiagnosticForNode(errorNameNode, Diagnostics.Property_0_of_exported_class_expression_may_not_be_private_or_protected, propertyName));
             }
         }
 
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index 4aee7a37a88..c5b74943dcd 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -2432,9 +2432,9 @@
         "category": "Error",
         "code": 4092
     },
-    "'extends' clause of exported class '{0}' refers to a type whose name cannot be referenced.": {
+    "Property '{0}' of exported class expression may not be private or protected.": {
         "category": "Error",
-        "code": 4093
+        "code": 4094
     },
 
     "The current host does not support the '{0}' option.": {
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index 069f8b967cf..0cade7f2cbc 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -2648,7 +2648,7 @@ namespace ts {
         // with import statements it previously saw (but chose not to emit).
         trackSymbol(symbol: Symbol, enclosingDeclaration?: Node, meaning?: SymbolFlags): void;
         reportInaccessibleThisError(): void;
-        reportIllegalExtends(): void;
+        reportPrivateInBaseOfClassExpression(propertyName: string): void;
     }
 
     export const enum TypeFormatFlags {
diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
index befb1c4ba77..3c3710c1cc5 100644
--- a/src/compiler/utilities.ts
+++ b/src/compiler/utilities.ts
@@ -68,7 +68,7 @@ namespace ts {
                 clear: () => str = "",
                 trackSymbol: noop,
                 reportInaccessibleThisError: noop,
-                reportIllegalExtends: noop
+                reportPrivateInBaseOfClassExpression: noop,
             };
         }
 
diff --git a/src/services/utilities.ts b/src/services/utilities.ts
index c8b710789ad..0965eb4dad7 100644
--- a/src/services/utilities.ts
+++ b/src/services/utilities.ts
@@ -1128,7 +1128,7 @@ namespace ts {
             clear: resetWriter,
             trackSymbol: noop,
             reportInaccessibleThisError: noop,
-            reportIllegalExtends: noop
+            reportPrivateInBaseOfClassExpression: noop,
         };
 
         function writeIndent() {