diff --git a/tests/baselines/reference/mergedInheritedClassInterface.js b/tests/baselines/reference/mergedInheritedClassInterface.js
new file mode 100644
index 00000000000..b3a15d1dfba
--- /dev/null
+++ b/tests/baselines/reference/mergedInheritedClassInterface.js
@@ -0,0 +1,39 @@
+//// [mergedInheritedClassInterface.ts]
+interface BaseInterface {
+    required: number;
+    optional?: number;
+}
+
+declare class BaseClass {
+    baseMethod();
+    x2: number;
+}
+
+interface Child extends BaseInterface {
+    x3: number;
+}
+
+declare class Child extends BaseClass {
+    x4: number;
+    method();
+}
+
+// checks if properties actually were merged
+var child : Child;
+child.required;
+child.optional;
+child.x3;
+child.x4;
+child.baseMethod();
+child.method();
+
+
+//// [mergedInheritedClassInterface.js]
+// checks if properties actually were merged
+var child;
+child.required;
+child.optional;
+child.x3;
+child.x4;
+child.baseMethod();
+child.method();
diff --git a/tests/baselines/reference/mergedInheritedClassInterface.symbols b/tests/baselines/reference/mergedInheritedClassInterface.symbols
new file mode 100644
index 00000000000..27ed4032a5f
--- /dev/null
+++ b/tests/baselines/reference/mergedInheritedClassInterface.symbols
@@ -0,0 +1,75 @@
+=== tests/cases/conformance/classes/classDeclarations/mergedInheritedClassInterface.ts ===
+interface BaseInterface {
+>BaseInterface : Symbol(BaseInterface, Decl(mergedInheritedClassInterface.ts, 0, 0))
+
+    required: number;
+>required : Symbol(required, Decl(mergedInheritedClassInterface.ts, 0, 25))
+
+    optional?: number;
+>optional : Symbol(optional, Decl(mergedInheritedClassInterface.ts, 1, 21))
+}
+
+declare class BaseClass {
+>BaseClass : Symbol(BaseClass, Decl(mergedInheritedClassInterface.ts, 3, 1))
+
+    baseMethod();
+>baseMethod : Symbol(baseMethod, Decl(mergedInheritedClassInterface.ts, 5, 25))
+
+    x2: number;
+>x2 : Symbol(x2, Decl(mergedInheritedClassInterface.ts, 6, 17))
+}
+
+interface Child extends BaseInterface {
+>Child : Symbol(Child, Decl(mergedInheritedClassInterface.ts, 8, 1), Decl(mergedInheritedClassInterface.ts, 12, 1))
+>BaseInterface : Symbol(BaseInterface, Decl(mergedInheritedClassInterface.ts, 0, 0))
+
+    x3: number;
+>x3 : Symbol(x3, Decl(mergedInheritedClassInterface.ts, 10, 39))
+}
+
+declare class Child extends BaseClass {
+>Child : Symbol(Child, Decl(mergedInheritedClassInterface.ts, 8, 1), Decl(mergedInheritedClassInterface.ts, 12, 1))
+>BaseClass : Symbol(BaseClass, Decl(mergedInheritedClassInterface.ts, 3, 1))
+
+    x4: number;
+>x4 : Symbol(x4, Decl(mergedInheritedClassInterface.ts, 14, 39))
+
+    method();
+>method : Symbol(method, Decl(mergedInheritedClassInterface.ts, 15, 15))
+}
+
+// checks if properties actually were merged
+var child : Child;
+>child : Symbol(child, Decl(mergedInheritedClassInterface.ts, 20, 3))
+>Child : Symbol(Child, Decl(mergedInheritedClassInterface.ts, 8, 1), Decl(mergedInheritedClassInterface.ts, 12, 1))
+
+child.required;
+>child.required : Symbol(BaseInterface.required, Decl(mergedInheritedClassInterface.ts, 0, 25))
+>child : Symbol(child, Decl(mergedInheritedClassInterface.ts, 20, 3))
+>required : Symbol(BaseInterface.required, Decl(mergedInheritedClassInterface.ts, 0, 25))
+
+child.optional;
+>child.optional : Symbol(BaseInterface.optional, Decl(mergedInheritedClassInterface.ts, 1, 21))
+>child : Symbol(child, Decl(mergedInheritedClassInterface.ts, 20, 3))
+>optional : Symbol(BaseInterface.optional, Decl(mergedInheritedClassInterface.ts, 1, 21))
+
+child.x3;
+>child.x3 : Symbol(Child.x3, Decl(mergedInheritedClassInterface.ts, 10, 39))
+>child : Symbol(child, Decl(mergedInheritedClassInterface.ts, 20, 3))
+>x3 : Symbol(Child.x3, Decl(mergedInheritedClassInterface.ts, 10, 39))
+
+child.x4;
+>child.x4 : Symbol(Child.x4, Decl(mergedInheritedClassInterface.ts, 14, 39))
+>child : Symbol(child, Decl(mergedInheritedClassInterface.ts, 20, 3))
+>x4 : Symbol(Child.x4, Decl(mergedInheritedClassInterface.ts, 14, 39))
+
+child.baseMethod();
+>child.baseMethod : Symbol(BaseClass.baseMethod, Decl(mergedInheritedClassInterface.ts, 5, 25))
+>child : Symbol(child, Decl(mergedInheritedClassInterface.ts, 20, 3))
+>baseMethod : Symbol(BaseClass.baseMethod, Decl(mergedInheritedClassInterface.ts, 5, 25))
+
+child.method();
+>child.method : Symbol(Child.method, Decl(mergedInheritedClassInterface.ts, 15, 15))
+>child : Symbol(child, Decl(mergedInheritedClassInterface.ts, 20, 3))
+>method : Symbol(Child.method, Decl(mergedInheritedClassInterface.ts, 15, 15))
+
diff --git a/tests/baselines/reference/mergedInheritedClassInterface.types b/tests/baselines/reference/mergedInheritedClassInterface.types
new file mode 100644
index 00000000000..bc0f619f843
--- /dev/null
+++ b/tests/baselines/reference/mergedInheritedClassInterface.types
@@ -0,0 +1,77 @@
+=== tests/cases/conformance/classes/classDeclarations/mergedInheritedClassInterface.ts ===
+interface BaseInterface {
+>BaseInterface : BaseInterface
+
+    required: number;
+>required : number
+
+    optional?: number;
+>optional : number
+}
+
+declare class BaseClass {
+>BaseClass : BaseClass
+
+    baseMethod();
+>baseMethod : () => any
+
+    x2: number;
+>x2 : number
+}
+
+interface Child extends BaseInterface {
+>Child : Child
+>BaseInterface : BaseInterface
+
+    x3: number;
+>x3 : number
+}
+
+declare class Child extends BaseClass {
+>Child : Child
+>BaseClass : BaseClass
+
+    x4: number;
+>x4 : number
+
+    method();
+>method : () => any
+}
+
+// checks if properties actually were merged
+var child : Child;
+>child : Child
+>Child : Child
+
+child.required;
+>child.required : number
+>child : Child
+>required : number
+
+child.optional;
+>child.optional : number
+>child : Child
+>optional : number
+
+child.x3;
+>child.x3 : number
+>child : Child
+>x3 : number
+
+child.x4;
+>child.x4 : number
+>child : Child
+>x4 : number
+
+child.baseMethod();
+>child.baseMethod() : any
+>child.baseMethod : () => any
+>child : Child
+>baseMethod : () => any
+
+child.method();
+>child.method() : any
+>child.method : () => any
+>child : Child
+>method : () => any
+
diff --git a/tests/cases/conformance/classes/classDeclarations/mergedInheritedClassInterface.ts b/tests/cases/conformance/classes/classDeclarations/mergedInheritedClassInterface.ts
new file mode 100644
index 00000000000..593edde7f20
--- /dev/null
+++ b/tests/cases/conformance/classes/classDeclarations/mergedInheritedClassInterface.ts
@@ -0,0 +1,27 @@
+interface BaseInterface {
+    required: number;
+    optional?: number;
+}
+
+declare class BaseClass {
+    baseMethod();
+    x2: number;
+}
+
+interface Child extends BaseInterface {
+    x3: number;
+}
+
+declare class Child extends BaseClass {
+    x4: number;
+    method();
+}
+
+// checks if properties actually were merged
+var child : Child;
+child.required;
+child.optional;
+child.x3;
+child.x4;
+child.baseMethod();
+child.method();