diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index a59abf22f1d..5e3aa294038 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -5894,7 +5894,7 @@ namespace ts {
                 return type.resolvedBaseTypes = emptyArray;
             }
             if (!isValidBaseType(baseType)) {
-                error(baseTypeNode.expression, Diagnostics.Base_constructor_return_type_0_is_not_a_class_or_interface_type, typeToString(baseType));
+                error(baseTypeNode.expression, Diagnostics.Base_constructor_return_type_0_is_not_an_object_type_or_intersection_of_object_types_with_statically_known_members, typeToString(baseType));
                 return type.resolvedBaseTypes = emptyArray;
             }
             if (type === baseType || hasBaseType(baseType, type)) {
@@ -5952,7 +5952,7 @@ namespace ts {
                                 }
                             }
                             else {
-                                error(node, Diagnostics.An_interface_may_only_extend_a_class_or_another_interface);
+                                error(node, Diagnostics.An_interface_can_only_extend_an_object_type_or_intersection_of_object_types_with_statically_known_members);
                             }
                         }
                     }
@@ -26454,7 +26454,7 @@ namespace ts {
                                 }
                             }
                             else {
-                                error(typeRefNode, Diagnostics.A_class_may_only_implement_another_class_or_interface);
+                                error(typeRefNode, Diagnostics.A_class_can_only_implement_an_object_type_or_intersection_of_object_types_with_statically_known_members);
                             }
                         }
                     }
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index 9078395a150..1845f2b601d 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -1060,7 +1060,7 @@
         "category": "Error",
         "code": 2311
     },
-    "An interface may only extend a class or another interface.": {
+    "An interface can only extend an object type or intersection of object types with statically known members.": {
         "category": "Error",
         "code": 2312
     },
@@ -1488,7 +1488,7 @@
         "category": "Error",
         "code": 2420
     },
-    "A class may only implement another class or interface.": {
+    "A class can only implement an object type or intersection of object types with statically known members.": {
         "category": "Error",
         "code": 2422
     },
@@ -1820,7 +1820,7 @@
         "category": "Error",
         "code": 2508
     },
-    "Base constructor return type '{0}' is not a class or interface type.": {
+    "Base constructor return type '{0}' is not an object type or intersection of object types with statically known members.": {
         "category": "Error",
         "code": 2509
     },
diff --git a/tests/baselines/reference/inheritFromGenericTypeParameter.errors.txt b/tests/baselines/reference/inheritFromGenericTypeParameter.errors.txt
index c043e37575c..f0618a06253 100644
--- a/tests/baselines/reference/inheritFromGenericTypeParameter.errors.txt
+++ b/tests/baselines/reference/inheritFromGenericTypeParameter.errors.txt
@@ -1,5 +1,5 @@
 tests/cases/compiler/inheritFromGenericTypeParameter.ts(1,20): error TS2304: Cannot find name 'T'.
-tests/cases/compiler/inheritFromGenericTypeParameter.ts(2,24): error TS2312: An interface may only extend a class or another interface.
+tests/cases/compiler/inheritFromGenericTypeParameter.ts(2,24): error TS2312: An interface can only extend an object type or intersection of object types with statically known members.
 
 
 ==== tests/cases/compiler/inheritFromGenericTypeParameter.ts (2 errors) ====
@@ -8,4 +8,4 @@ tests/cases/compiler/inheritFromGenericTypeParameter.ts(2,24): error TS2312: An
 !!! error TS2304: Cannot find name 'T'.
     interface I<T> extends T { }
                            ~
-!!! error TS2312: An interface may only extend a class or another interface.
\ No newline at end of file
+!!! error TS2312: An interface can only extend an object type or intersection of object types with statically known members.
\ No newline at end of file
diff --git a/tests/baselines/reference/interfaceExtendsObjectIntersectionErrors.errors.txt b/tests/baselines/reference/interfaceExtendsObjectIntersectionErrors.errors.txt
index 87faadeb4a6..17cb5585cf8 100644
--- a/tests/baselines/reference/interfaceExtendsObjectIntersectionErrors.errors.txt
+++ b/tests/baselines/reference/interfaceExtendsObjectIntersectionErrors.errors.txt
@@ -51,8 +51,8 @@ tests/cases/conformance/interfaces/interfaceDeclarations/interfaceExtendsObjectI
   Type 'I23' is not assignable to type 'T1'.
     Types of property 'a' are incompatible.
       Type 'string' is not assignable to type 'number'.
-tests/cases/conformance/interfaces/interfaceDeclarations/interfaceExtendsObjectIntersectionErrors.ts(46,23): error TS2312: An interface may only extend a class or another interface.
-tests/cases/conformance/interfaces/interfaceDeclarations/interfaceExtendsObjectIntersectionErrors.ts(47,26): error TS2312: An interface may only extend a class or another interface.
+tests/cases/conformance/interfaces/interfaceDeclarations/interfaceExtendsObjectIntersectionErrors.ts(46,23): error TS2312: An interface can only extend an object type or intersection of object types with statically known members.
+tests/cases/conformance/interfaces/interfaceDeclarations/interfaceExtendsObjectIntersectionErrors.ts(47,26): error TS2312: An interface can only extend an object type or intersection of object types with statically known members.
 
 
 ==== tests/cases/conformance/interfaces/interfaceDeclarations/interfaceExtendsObjectIntersectionErrors.ts (23 errors) ====
@@ -177,8 +177,8 @@ tests/cases/conformance/interfaces/interfaceDeclarations/interfaceExtendsObjectI
     
     interface I30 extends U { x: string }
                           ~
-!!! error TS2312: An interface may only extend a class or another interface.
+!!! error TS2312: An interface can only extend an object type or intersection of object types with statically known members.
     interface I31<T> extends T { x: string }
                              ~
-!!! error TS2312: An interface may only extend a class or another interface.
+!!! error TS2312: An interface can only extend an object type or intersection of object types with statically known members.
     
\ No newline at end of file
diff --git a/tests/baselines/reference/typeParameterAsBaseClass.errors.txt b/tests/baselines/reference/typeParameterAsBaseClass.errors.txt
index dec7f7f2a4a..9a8706b4c93 100644
--- a/tests/baselines/reference/typeParameterAsBaseClass.errors.txt
+++ b/tests/baselines/reference/typeParameterAsBaseClass.errors.txt
@@ -1,5 +1,5 @@
 tests/cases/compiler/typeParameterAsBaseClass.ts(1,20): error TS2304: Cannot find name 'T'.
-tests/cases/compiler/typeParameterAsBaseClass.ts(2,24): error TS2422: A class may only implement another class or interface.
+tests/cases/compiler/typeParameterAsBaseClass.ts(2,24): error TS2422: A class can only implement an object type or intersection of object types with statically known members.
 
 
 ==== tests/cases/compiler/typeParameterAsBaseClass.ts (2 errors) ====
@@ -8,4 +8,4 @@ tests/cases/compiler/typeParameterAsBaseClass.ts(2,24): error TS2422: A class ma
 !!! error TS2304: Cannot find name 'T'.
     class C2<T> implements T {}
                            ~
-!!! error TS2422: A class may only implement another class or interface.
\ No newline at end of file
+!!! error TS2422: A class can only implement an object type or intersection of object types with statically known members.
\ No newline at end of file
diff --git a/tests/baselines/reference/typeParameterAsBaseType.errors.txt b/tests/baselines/reference/typeParameterAsBaseType.errors.txt
index 835b2369948..63a1ab8bd14 100644
--- a/tests/baselines/reference/typeParameterAsBaseType.errors.txt
+++ b/tests/baselines/reference/typeParameterAsBaseType.errors.txt
@@ -1,7 +1,7 @@
 tests/cases/conformance/types/typeParameters/typeParameterAsBaseType.ts(4,20): error TS2304: Cannot find name 'T'.
 tests/cases/conformance/types/typeParameters/typeParameterAsBaseType.ts(5,24): error TS2304: Cannot find name 'U'.
-tests/cases/conformance/types/typeParameters/typeParameterAsBaseType.ts(7,24): error TS2312: An interface may only extend a class or another interface.
-tests/cases/conformance/types/typeParameters/typeParameterAsBaseType.ts(8,28): error TS2312: An interface may only extend a class or another interface.
+tests/cases/conformance/types/typeParameters/typeParameterAsBaseType.ts(7,24): error TS2312: An interface can only extend an object type or intersection of object types with statically known members.
+tests/cases/conformance/types/typeParameters/typeParameterAsBaseType.ts(8,28): error TS2312: An interface can only extend an object type or intersection of object types with statically known members.
 
 
 ==== tests/cases/conformance/types/typeParameters/typeParameterAsBaseType.ts (4 errors) ====
@@ -17,9 +17,9 @@ tests/cases/conformance/types/typeParameters/typeParameterAsBaseType.ts(8,28): e
     
     interface I<T> extends T { }
                            ~
-!!! error TS2312: An interface may only extend a class or another interface.
+!!! error TS2312: An interface can only extend an object type or intersection of object types with statically known members.
     interface I2<T, U> extends U { }
                                ~
-!!! error TS2312: An interface may only extend a class or another interface.
+!!! error TS2312: An interface can only extend an object type or intersection of object types with statically known members.
     
     
\ No newline at end of file