diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index eddddb5cb2b..dbce5f41ef4 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -14013,7 +14013,7 @@ namespace ts {
             }
         }
 
-        // Check each type parameter and check that list has no duplicate type parameter declarations
+        /** Check each type parameter and check that type parameters have no duplicate type parameter declarations */
         function checkTypeParameters(typeParameterDeclarations: TypeParameterDeclaration[]) {
             if (typeParameterDeclarations) {
                 for (let i = 0, n = typeParameterDeclarations.length; i < n; i++) {
@@ -14031,6 +14031,24 @@ namespace ts {
             }
         }
 
+        /** Check that type parameter lists are identical across multiple declarations */
+        function checkTypeParameterListsIdentical(node: ClassLikeDeclaration | InterfaceDeclaration, symbol: Symbol) {
+            if (symbol.declarations.length === 1) {
+                return;
+            }
+            let firstDecl: ClassLikeDeclaration | InterfaceDeclaration;
+            for (const declaration of symbol.declarations) {
+                if (declaration.kind === SyntaxKind.ClassDeclaration || declaration.kind === SyntaxKind.InterfaceDeclaration) {
+                    if (!firstDecl) {
+                        firstDecl = <ClassLikeDeclaration | InterfaceDeclaration>declaration;
+                    }
+                    else if (!areTypeParametersIdentical(firstDecl.typeParameters, node.typeParameters)) {
+                        error(node.name, Diagnostics.All_declarations_of_0_must_have_identical_type_parameters, node.name.text);
+                    }
+                }
+            }
+        }
+
         function checkClassExpression(node: ClassExpression): Type {
             checkClassLikeDeclaration(node);
             checkNodeDeferred(node);
@@ -14064,6 +14082,7 @@ namespace ts {
             const type = <InterfaceType>getDeclaredTypeOfSymbol(symbol);
             const typeWithThis = getTypeWithThisArgument(type);
             const staticType = <ObjectType>getTypeOfSymbol(symbol);
+            checkTypeParameterListsIdentical(node, symbol);
 
             const baseTypeNode = getClassExtendsHeritageClauseElement(node);
             if (baseTypeNode) {
@@ -14326,14 +14345,10 @@ namespace ts {
 
                 checkExportsOnMergedDeclarations(node);
                 const symbol = getSymbolOfNode(node);
-                const firstInterfaceDecl = <InterfaceDeclaration>getDeclarationOfKind(symbol, SyntaxKind.InterfaceDeclaration);
-                if (symbol.declarations.length > 1) {
-                    if (node !== firstInterfaceDecl && !areTypeParametersIdentical(firstInterfaceDecl.typeParameters, node.typeParameters)) {
-                        error(node.name, Diagnostics.All_declarations_of_an_interface_must_have_identical_type_parameters);
-                    }
-                }
+                checkTypeParameterListsIdentical(node, symbol);
 
                 // Only check this symbol once
+                const firstInterfaceDecl = <InterfaceDeclaration>getDeclarationOfKind(symbol, SyntaxKind.InterfaceDeclaration);
                 if (node === firstInterfaceDecl) {
                     const type = <InterfaceType>getDeclaredTypeOfSymbol(symbol);
                     const typeWithThis = getTypeWithThisArgument(type);
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index 16cf1911642..70c6d8ff167 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -1311,7 +1311,7 @@
         "category": "Error",
         "code": 2427
     },
-    "All declarations of an interface must have identical type parameters.": {
+    "All declarations of '{0}' must have identical type parameters.": {
         "category": "Error",
         "code": 2428
     },
@@ -2801,4 +2801,4 @@
         "category": "Error",
         "code": 17009
     }
-}
+}
diff --git a/tests/baselines/reference/constructSignaturesWithOverloads2.errors.txt b/tests/baselines/reference/constructSignaturesWithOverloads2.errors.txt
index ceb828dd061..617f7b1502f 100644
--- a/tests/baselines/reference/constructSignaturesWithOverloads2.errors.txt
+++ b/tests/baselines/reference/constructSignaturesWithOverloads2.errors.txt
@@ -1,4 +1,4 @@
-tests/cases/conformance/types/objectTypeLiteral/constructSignatures/constructSignaturesWithOverloads2.ts(32,11): error TS2428: All declarations of an interface must have identical type parameters.
+tests/cases/conformance/types/objectTypeLiteral/constructSignatures/constructSignaturesWithOverloads2.ts(32,11): error TS2428: All declarations of 'I' must have identical type parameters.
 
 
 ==== tests/cases/conformance/types/objectTypeLiteral/constructSignatures/constructSignaturesWithOverloads2.ts (1 errors) ====
@@ -35,7 +35,7 @@ tests/cases/conformance/types/objectTypeLiteral/constructSignatures/constructSig
     
     interface I<T> {
               ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations of 'I' must have identical type parameters.
         new (x: T, y?: number): C2<T>;
         new (x: T, y: number): C2<T>;
     }
diff --git a/tests/baselines/reference/extendedInterfacesWithDuplicateTypeParameters.errors.txt b/tests/baselines/reference/extendedInterfacesWithDuplicateTypeParameters.errors.txt
index 7d7fea1b2c6..7b47fee05af 100644
--- a/tests/baselines/reference/extendedInterfacesWithDuplicateTypeParameters.errors.txt
+++ b/tests/baselines/reference/extendedInterfacesWithDuplicateTypeParameters.errors.txt
@@ -1,5 +1,5 @@
 tests/cases/compiler/extendedInterfacesWithDuplicateTypeParameters.ts(1,42): error TS2300: Duplicate identifier 'A'.
-tests/cases/compiler/extendedInterfacesWithDuplicateTypeParameters.ts(9,11): error TS2428: All declarations of an interface must have identical type parameters.
+tests/cases/compiler/extendedInterfacesWithDuplicateTypeParameters.ts(9,11): error TS2428: All declarations of 'InterfaceWithSomeTypars' must have identical type parameters.
 tests/cases/compiler/extendedInterfacesWithDuplicateTypeParameters.ts(9,38): error TS2300: Duplicate identifier 'C'.
 
 
@@ -16,7 +16,7 @@ tests/cases/compiler/extendedInterfacesWithDuplicateTypeParameters.ts(9,38): err
     
     interface InterfaceWithSomeTypars<C, C> { // should error
               ~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations of 'InterfaceWithSomeTypars' must have identical type parameters.
                                          ~
 !!! error TS2300: Duplicate identifier 'C'.
     	bar2(): void;
diff --git a/tests/baselines/reference/genericAndNonGenericInterfaceWithTheSameName.errors.txt b/tests/baselines/reference/genericAndNonGenericInterfaceWithTheSameName.errors.txt
index 4c3245b11f7..8d9ebb8d276 100644
--- a/tests/baselines/reference/genericAndNonGenericInterfaceWithTheSameName.errors.txt
+++ b/tests/baselines/reference/genericAndNonGenericInterfaceWithTheSameName.errors.txt
@@ -1,6 +1,6 @@
-tests/cases/conformance/interfaces/declarationMerging/genericAndNonGenericInterfaceWithTheSameName.ts(7,11): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/conformance/interfaces/declarationMerging/genericAndNonGenericInterfaceWithTheSameName.ts(16,15): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/conformance/interfaces/declarationMerging/genericAndNonGenericInterfaceWithTheSameName.ts(40,22): error TS2428: All declarations of an interface must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/genericAndNonGenericInterfaceWithTheSameName.ts(7,11): error TS2428: All declarations of 'A' must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/genericAndNonGenericInterfaceWithTheSameName.ts(16,15): error TS2428: All declarations of 'A' must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/genericAndNonGenericInterfaceWithTheSameName.ts(40,22): error TS2428: All declarations of 'A' must have identical type parameters.
 
 
 ==== tests/cases/conformance/interfaces/declarationMerging/genericAndNonGenericInterfaceWithTheSameName.ts (3 errors) ====
@@ -12,7 +12,7 @@ tests/cases/conformance/interfaces/declarationMerging/genericAndNonGenericInterf
     
     interface A<T> { // error
               ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations of 'A' must have identical type parameters.
         bar: T;
     }
     
@@ -23,7 +23,7 @@ tests/cases/conformance/interfaces/declarationMerging/genericAndNonGenericInterf
     
         interface A { // error
                   ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations of 'A' must have identical type parameters.
             foo: string;
         }
     }
@@ -49,7 +49,7 @@ tests/cases/conformance/interfaces/declarationMerging/genericAndNonGenericInterf
     module M3 {
         export interface A<T> { // error
                          ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations of 'A' must have identical type parameters.
             bar: T;
         }
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/interfaceWithMultipleDeclarations.errors.txt b/tests/baselines/reference/interfaceWithMultipleDeclarations.errors.txt
index e4b37db8a7a..79d8b4a509a 100644
--- a/tests/baselines/reference/interfaceWithMultipleDeclarations.errors.txt
+++ b/tests/baselines/reference/interfaceWithMultipleDeclarations.errors.txt
@@ -1,14 +1,14 @@
-tests/cases/compiler/interfaceWithMultipleDeclarations.ts(3,11): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/compiler/interfaceWithMultipleDeclarations.ts(5,11): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/compiler/interfaceWithMultipleDeclarations.ts(7,11): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/compiler/interfaceWithMultipleDeclarations.ts(9,11): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/compiler/interfaceWithMultipleDeclarations.ts(11,11): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/compiler/interfaceWithMultipleDeclarations.ts(16,11): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/compiler/interfaceWithMultipleDeclarations.ts(18,11): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/compiler/interfaceWithMultipleDeclarations.ts(20,11): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/compiler/interfaceWithMultipleDeclarations.ts(22,11): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/compiler/interfaceWithMultipleDeclarations.ts(24,11): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/compiler/interfaceWithMultipleDeclarations.ts(29,11): error TS2428: All declarations of an interface must have identical type parameters.
+tests/cases/compiler/interfaceWithMultipleDeclarations.ts(3,11): error TS2428: All declarations of 'I1' must have identical type parameters.
+tests/cases/compiler/interfaceWithMultipleDeclarations.ts(5,11): error TS2428: All declarations of 'I1' must have identical type parameters.
+tests/cases/compiler/interfaceWithMultipleDeclarations.ts(7,11): error TS2428: All declarations of 'I1' must have identical type parameters.
+tests/cases/compiler/interfaceWithMultipleDeclarations.ts(9,11): error TS2428: All declarations of 'I1' must have identical type parameters.
+tests/cases/compiler/interfaceWithMultipleDeclarations.ts(11,11): error TS2428: All declarations of 'I1' must have identical type parameters.
+tests/cases/compiler/interfaceWithMultipleDeclarations.ts(16,11): error TS2428: All declarations of 'I2' must have identical type parameters.
+tests/cases/compiler/interfaceWithMultipleDeclarations.ts(18,11): error TS2428: All declarations of 'I2' must have identical type parameters.
+tests/cases/compiler/interfaceWithMultipleDeclarations.ts(20,11): error TS2428: All declarations of 'I2' must have identical type parameters.
+tests/cases/compiler/interfaceWithMultipleDeclarations.ts(22,11): error TS2428: All declarations of 'I2' must have identical type parameters.
+tests/cases/compiler/interfaceWithMultipleDeclarations.ts(24,11): error TS2428: All declarations of 'I2' must have identical type parameters.
+tests/cases/compiler/interfaceWithMultipleDeclarations.ts(29,11): error TS2428: All declarations of 'I3' must have identical type parameters.
 
 
 ==== tests/cases/compiler/interfaceWithMultipleDeclarations.ts (11 errors) ====
@@ -16,53 +16,53 @@ tests/cases/compiler/interfaceWithMultipleDeclarations.ts(29,11): error TS2428:
     }
     interface I1<S> { // Name mismatch
               ~~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations of 'I1' must have identical type parameters.
     }
     interface I1<T, U extends T> { // Length mismatch
               ~~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations of 'I1' must have identical type parameters.
     }
     interface I1<V extends string> { // constraint present
               ~~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations of 'I1' must have identical type parameters.
     }
     interface I1<V, X extends V> { // Length mismatch
               ~~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations of 'I1' must have identical type parameters.
     }
     interface I1 { // Length mismatch
               ~~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations of 'I1' must have identical type parameters.
     }
     
     interface I2<T extends string> {
     }
     interface I2<T extends () => string> { // constraint mismatch
               ~~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations of 'I2' must have identical type parameters.
     }
     interface I2<T> { // constraint absent
               ~~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations of 'I2' must have identical type parameters.
     }
     interface I2<U> { // name mismatch
               ~~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations of 'I2' must have identical type parameters.
     }
     interface I2<X, Y> { // length mismatch
               ~~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations of 'I2' must have identical type parameters.
     }
     interface I2 { // length mismatch
               ~~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations of 'I2' must have identical type parameters.
     }
     
     interface I3 {
     }
     interface I3<T> { // length mismatch
               ~~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations of 'I3' must have identical type parameters.
     }
     
     class Foo<T> {
diff --git a/tests/baselines/reference/multipleNumericIndexers.errors.txt b/tests/baselines/reference/multipleNumericIndexers.errors.txt
index 856fdbe47ff..82fc444ac65 100644
--- a/tests/baselines/reference/multipleNumericIndexers.errors.txt
+++ b/tests/baselines/reference/multipleNumericIndexers.errors.txt
@@ -3,7 +3,7 @@ tests/cases/conformance/types/objectTypeLiteral/indexSignatures/multipleNumericI
 tests/cases/conformance/types/objectTypeLiteral/indexSignatures/multipleNumericIndexers.ts(15,5): error TS2375: Duplicate number index signature.
 tests/cases/conformance/types/objectTypeLiteral/indexSignatures/multipleNumericIndexers.ts(20,5): error TS2375: Duplicate number index signature.
 tests/cases/conformance/types/objectTypeLiteral/indexSignatures/multipleNumericIndexers.ts(25,5): error TS2375: Duplicate number index signature.
-tests/cases/conformance/types/objectTypeLiteral/indexSignatures/multipleNumericIndexers.ts(28,11): error TS2428: All declarations of an interface must have identical type parameters.
+tests/cases/conformance/types/objectTypeLiteral/indexSignatures/multipleNumericIndexers.ts(28,11): error TS2428: All declarations of 'I' must have identical type parameters.
 tests/cases/conformance/types/objectTypeLiteral/indexSignatures/multipleNumericIndexers.ts(29,5): error TS2375: Duplicate number index signature.
 tests/cases/conformance/types/objectTypeLiteral/indexSignatures/multipleNumericIndexers.ts(30,5): error TS2375: Duplicate number index signature.
 
@@ -48,7 +48,7 @@ tests/cases/conformance/types/objectTypeLiteral/indexSignatures/multipleNumericI
     
     interface I<T> {
               ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations of 'I' must have identical type parameters.
         [x: number]: string;
         ~~~~~~~~~~~~~~~~~~~~
 !!! error TS2375: Duplicate number index signature.
diff --git a/tests/baselines/reference/nonIdenticalTypeConstraints.errors.txt b/tests/baselines/reference/nonIdenticalTypeConstraints.errors.txt
new file mode 100644
index 00000000000..627b38579a2
--- /dev/null
+++ b/tests/baselines/reference/nonIdenticalTypeConstraints.errors.txt
@@ -0,0 +1,50 @@
+tests/cases/compiler/nonIdenticalTypeConstraints.ts(10,11): error TS2428: All declarations of 'Foo' must have identical type parameters.
+tests/cases/compiler/nonIdenticalTypeConstraints.ts(16,7): error TS2428: All declarations of 'Qux' must have identical type parameters.
+tests/cases/compiler/nonIdenticalTypeConstraints.ts(36,11): error TS2428: All declarations of 'Quux' must have identical type parameters.
+
+
+==== tests/cases/compiler/nonIdenticalTypeConstraints.ts (3 errors) ====
+    class Different {
+        a: number;
+        b: string;
+        c: boolean;
+    }
+    
+    class Foo<T extends Function> {
+        n: T;
+    }
+    interface Foo<T extends Different> {
+              ~~~
+!!! error TS2428: All declarations of 'Foo' must have identical type parameters.
+        y: T;
+    }
+    interface Qux<T extends Different> {
+        y: T;
+    }
+    class Qux<T extends Function> {
+          ~~~
+!!! error TS2428: All declarations of 'Qux' must have identical type parameters.
+        n: T;
+    }
+    
+    class Bar<T extends Function> {
+        n: T;
+    }
+    interface Bar<T extends Function> {
+        y: T;
+    }
+    interface Baz<T extends Function> {
+        y: T;
+    }
+    class Baz<T extends Function> {
+        n: T;
+    }
+    
+    class Quux<T> {
+        n: T;
+    }
+    interface Quux<U> {
+              ~~~~
+!!! error TS2428: All declarations of 'Quux' must have identical type parameters.
+        m: U;
+    }
\ No newline at end of file
diff --git a/tests/baselines/reference/nonIdenticalTypeConstraints.js b/tests/baselines/reference/nonIdenticalTypeConstraints.js
new file mode 100644
index 00000000000..73748f63885
--- /dev/null
+++ b/tests/baselines/reference/nonIdenticalTypeConstraints.js
@@ -0,0 +1,71 @@
+//// [nonIdenticalTypeConstraints.ts]
+class Different {
+    a: number;
+    b: string;
+    c: boolean;
+}
+
+class Foo<T extends Function> {
+    n: T;
+}
+interface Foo<T extends Different> {
+    y: T;
+}
+interface Qux<T extends Different> {
+    y: T;
+}
+class Qux<T extends Function> {
+    n: T;
+}
+
+class Bar<T extends Function> {
+    n: T;
+}
+interface Bar<T extends Function> {
+    y: T;
+}
+interface Baz<T extends Function> {
+    y: T;
+}
+class Baz<T extends Function> {
+    n: T;
+}
+
+class Quux<T> {
+    n: T;
+}
+interface Quux<U> {
+    m: U;
+}
+
+//// [nonIdenticalTypeConstraints.js]
+var Different = (function () {
+    function Different() {
+    }
+    return Different;
+}());
+var Foo = (function () {
+    function Foo() {
+    }
+    return Foo;
+}());
+var Qux = (function () {
+    function Qux() {
+    }
+    return Qux;
+}());
+var Bar = (function () {
+    function Bar() {
+    }
+    return Bar;
+}());
+var Baz = (function () {
+    function Baz() {
+    }
+    return Baz;
+}());
+var Quux = (function () {
+    function Quux() {
+    }
+    return Quux;
+}());
diff --git a/tests/baselines/reference/twoGenericInterfacesDifferingByTypeParameterName.errors.txt b/tests/baselines/reference/twoGenericInterfacesDifferingByTypeParameterName.errors.txt
index adf9583095d..6c0f562ac64 100644
--- a/tests/baselines/reference/twoGenericInterfacesDifferingByTypeParameterName.errors.txt
+++ b/tests/baselines/reference/twoGenericInterfacesDifferingByTypeParameterName.errors.txt
@@ -1,8 +1,8 @@
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName.ts(7,11): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName.ts(15,11): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName.ts(24,15): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName.ts(32,15): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName.ts(56,22): error TS2428: All declarations of an interface must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName.ts(7,11): error TS2428: All declarations of 'A' must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName.ts(15,11): error TS2428: All declarations of 'B' must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName.ts(24,15): error TS2428: All declarations of 'A' must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName.ts(32,15): error TS2428: All declarations of 'B' must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName.ts(56,22): error TS2428: All declarations of 'B' must have identical type parameters.
 
 
 ==== tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName.ts (5 errors) ====
@@ -14,7 +14,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDiffer
     
     interface A<U> { // error
               ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations of 'A' must have identical type parameters.
         y: U;
     }
     
@@ -24,7 +24,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDiffer
     
     interface B<T,V> { // error
               ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations of 'B' must have identical type parameters.
         y: V;
     }
     
@@ -35,7 +35,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDiffer
     
         interface A<U> { // error
                   ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations of 'A' must have identical type parameters.
             y: U;
         }
     
@@ -45,7 +45,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDiffer
     
         interface B<T, V> { // error
                   ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations of 'B' must have identical type parameters.
             y: V;
         }
     }
@@ -71,7 +71,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDiffer
     module M3 {
         export interface B<T, V> { // error
                          ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations of 'B' must have identical type parameters.
             y: V;
         }
     }
diff --git a/tests/baselines/reference/twoGenericInterfacesDifferingByTypeParameterName2.errors.txt b/tests/baselines/reference/twoGenericInterfacesDifferingByTypeParameterName2.errors.txt
index dd1483b9e1d..f2a0063c230 100644
--- a/tests/baselines/reference/twoGenericInterfacesDifferingByTypeParameterName2.errors.txt
+++ b/tests/baselines/reference/twoGenericInterfacesDifferingByTypeParameterName2.errors.txt
@@ -1,7 +1,7 @@
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName2.ts(7,11): error TS2428: All declarations of an interface must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName2.ts(7,11): error TS2428: All declarations of 'B' must have identical type parameters.
 tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName2.ts(8,8): error TS2304: Cannot find name 'V'.
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName2.ts(16,15): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName2.ts(40,22): error TS2428: All declarations of an interface must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName2.ts(16,15): error TS2428: All declarations of 'B' must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName2.ts(40,22): error TS2428: All declarations of 'B' must have identical type parameters.
 
 
 ==== tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName2.ts (4 errors) ====
@@ -13,7 +13,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDiffer
     
     interface B<U, T> { // error
               ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations of 'B' must have identical type parameters.
         y: V;
            ~
 !!! error TS2304: Cannot find name 'V'.
@@ -26,7 +26,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDiffer
     
         interface B<U, T> { // error
                   ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations of 'B' must have identical type parameters.
             y: T;
         }
     }
@@ -52,7 +52,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDiffer
     module M3 {
         export interface B<U, T> { // error
                          ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations of 'B' must have identical type parameters.
             y: T;
         }
     }
diff --git a/tests/baselines/reference/twoGenericInterfacesWithDifferentConstraints.errors.txt b/tests/baselines/reference/twoGenericInterfacesWithDifferentConstraints.errors.txt
index 665a26f47f4..4b2455773f5 100644
--- a/tests/baselines/reference/twoGenericInterfacesWithDifferentConstraints.errors.txt
+++ b/tests/baselines/reference/twoGenericInterfacesWithDifferentConstraints.errors.txt
@@ -1,6 +1,6 @@
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithDifferentConstraints.ts(5,11): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithDifferentConstraints.ts(14,15): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithDifferentConstraints.ts(38,22): error TS2428: All declarations of an interface must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithDifferentConstraints.ts(5,11): error TS2428: All declarations of 'A' must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithDifferentConstraints.ts(14,15): error TS2428: All declarations of 'B' must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithDifferentConstraints.ts(38,22): error TS2428: All declarations of 'A' must have identical type parameters.
 
 
 ==== tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithDifferentConstraints.ts (3 errors) ====
@@ -10,7 +10,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithDi
     
     interface A<T extends Number> { // error
               ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations of 'A' must have identical type parameters.
         y: T;
     }
     
@@ -21,7 +21,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithDi
     
         interface B<T extends A<any>> { // error
                   ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations of 'B' must have identical type parameters.
             y: T;
         }
     }
@@ -47,7 +47,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithDi
     module M3 {
         export interface A<T extends Number> { // error
                          ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations of 'A' must have identical type parameters.
             y: T;
         }
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/twoGenericInterfacesWithTheSameNameButDifferentArity.errors.txt b/tests/baselines/reference/twoGenericInterfacesWithTheSameNameButDifferentArity.errors.txt
index be0608c0cd6..de4c4d8e1c3 100644
--- a/tests/baselines/reference/twoGenericInterfacesWithTheSameNameButDifferentArity.errors.txt
+++ b/tests/baselines/reference/twoGenericInterfacesWithTheSameNameButDifferentArity.errors.txt
@@ -1,6 +1,6 @@
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithTheSameNameButDifferentArity.ts(5,11): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithTheSameNameButDifferentArity.ts(14,15): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithTheSameNameButDifferentArity.ts(38,22): error TS2428: All declarations of an interface must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithTheSameNameButDifferentArity.ts(5,11): error TS2428: All declarations of 'A' must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithTheSameNameButDifferentArity.ts(14,15): error TS2428: All declarations of 'A' must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithTheSameNameButDifferentArity.ts(38,22): error TS2428: All declarations of 'A' must have identical type parameters.
 
 
 ==== tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithTheSameNameButDifferentArity.ts (3 errors) ====
@@ -10,7 +10,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithTh
     
     interface A<T, U> { // error
               ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations of 'A' must have identical type parameters.
         y: T;
     }
     
@@ -21,7 +21,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithTh
     
         interface A<T, U> { // error
                   ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations of 'A' must have identical type parameters.
             y: T;
         }
     }
@@ -47,7 +47,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithTh
     module M3 {
         export interface A<T, U> { // error
                          ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations of 'A' must have identical type parameters.
             y: T;
         }
     }
\ No newline at end of file
diff --git a/tests/cases/compiler/nonIdenticalTypeConstraints.ts b/tests/cases/compiler/nonIdenticalTypeConstraints.ts
new file mode 100644
index 00000000000..c0271edc91a
--- /dev/null
+++ b/tests/cases/compiler/nonIdenticalTypeConstraints.ts
@@ -0,0 +1,38 @@
+class Different {
+    a: number;
+    b: string;
+    c: boolean;
+}
+
+class Foo<T extends Function> {
+    n: T;
+}
+interface Foo<T extends Different> {
+    y: T;
+}
+interface Qux<T extends Different> {
+    y: T;
+}
+class Qux<T extends Function> {
+    n: T;
+}
+
+class Bar<T extends Function> {
+    n: T;
+}
+interface Bar<T extends Function> {
+    y: T;
+}
+interface Baz<T extends Function> {
+    y: T;
+}
+class Baz<T extends Function> {
+    n: T;
+}
+
+class Quux<T> {
+    n: T;
+}
+interface Quux<U> {
+    m: U;
+}
\ No newline at end of file