diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 2351f6913af..5c69bb7f356 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -10182,10 +10182,10 @@ namespace ts {
             // A private or protected constructor can only be instantiated within it's own class 
             if (declaringClass !== enclosingClass) {
                 if (flags & NodeFlags.Private) {
-                    error(node, Diagnostics.Constructor_of_type_0_is_private_and_only_accessible_within_class_1, signatureToString(signature), typeToString(declaringClass));
+                    error(node, Diagnostics.Constructor_of_class_0_is_private_and_only_accessible_within_the_class_declaration, typeToString(declaringClass));
                 }
                 if (flags & NodeFlags.Protected) {
-                    error(node, Diagnostics.Constructor_of_type_0_is_protected_and_only_accessible_within_class_1, signatureToString(signature), typeToString(declaringClass));
+                    error(node, Diagnostics.Constructor_of_class_0_is_protected_and_only_accessible_within_the_class_declaration, typeToString(declaringClass));
                 }
                 return false;
             }
@@ -14059,7 +14059,7 @@ namespace ts {
             if (signatures.length) {
                 const declaration = signatures[0].declaration;
                 if (declaration && declaration.flags & NodeFlags.Private) {
-                    error(node, Diagnostics.Cannot_extend_private_class_0, (<Identifier>node.expression).text);
+                    error(node, Diagnostics.Cannot_extend_a_class_0_Class_constructor_is_marked_as_private, (<Identifier>node.expression).text);
                 }
             }
         }
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index 2ee388ff42e..b88b9b2a0e1 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -1827,15 +1827,15 @@
         "category": "Error",
         "code": 2672
     },
-    "Constructor of type '{0}' is private and only accessible within class '{1}'.": {
+    "Constructor of class '{0}' is private and only accessible within the class declaration.": {
         "category": "Error",
         "code": 2673
     },
-    "Constructor of type '{0}' is protected and only accessible within class '{1}'.": {
+    "Constructor of class '{0}' is protected and only accessible within the class declaration.": {
         "category": "Error",
         "code": 2674
     },
-    "Cannot extend private class '{0}'.": {
+    "Cannot extend a class '{0}'. Class constructor is marked as private.": {
         "category": "Error",
         "code": 2675
     },