diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 187a53b12ef..53c9b066caf 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -15596,6 +15596,9 @@ namespace ts {
                 case SyntaxKind.InterfaceDeclaration:
                 case SyntaxKind.ModuleDeclaration:
                 case SyntaxKind.TypeAliasDeclaration:
+                    if (isGlobalAugmentation) {
+                        return;
+                    }
                     const symbol = getSymbolOfNode(node);
                     if (symbol) {
                         // module augmentations cannot introduce new names on the top level scope of the module
@@ -15604,14 +15607,8 @@ namespace ts {
                         // 2. main check - report error if value declaration of the parent symbol is module augmentation)
                         let reportError = !(symbol.flags & SymbolFlags.Merged);
                         if (!reportError) {
-                            if (isGlobalAugmentation) {
-                                // global symbol should not have parent since it is not explicitly exported
-                                reportError = symbol.parent !== undefined;
-                            }
-                            else {
-                                // symbol should not originate in augmentation
-                                reportError = isExternalModuleAugmentation(symbol.parent.declarations[0]);
-                            }
+                            // symbol should not originate in augmentation
+                            reportError = isExternalModuleAugmentation(symbol.parent.declarations[0]);
                         }
                         if (reportError) {
                             error(node, Diagnostics.Module_augmentation_cannot_introduce_new_names_in_the_top_level_scope);
diff --git a/tests/baselines/reference/moduleAugmentationGlobal4.errors.txt b/tests/baselines/reference/moduleAugmentationGlobal4.errors.txt
deleted file mode 100644
index fd3444f56b1..00000000000
--- a/tests/baselines/reference/moduleAugmentationGlobal4.errors.txt
+++ /dev/null
@@ -1,25 +0,0 @@
-tests/cases/compiler/f1.ts(3,15): error TS2665: Module augmentation cannot introduce new names in the top level scope.
-tests/cases/compiler/f2.ts(3,15): error TS2665: Module augmentation cannot introduce new names in the top level scope.
-
-
-==== tests/cases/compiler/f1.ts (1 errors) ====
-    
-    declare global {
-        interface Something {x}
-                  ~~~~~~~~~
-!!! error TS2665: Module augmentation cannot introduce new names in the top level scope.
-    }
-    export {};
-==== tests/cases/compiler/f2.ts (1 errors) ====
-    
-    declare global {
-        interface Something {y}
-                  ~~~~~~~~~
-!!! error TS2665: Module augmentation cannot introduce new names in the top level scope.
-    }
-    export {};
-==== tests/cases/compiler/f3.ts (0 errors) ====
-    import "./f1";
-    import "./f2";
-    
-    
\ No newline at end of file
diff --git a/tests/baselines/reference/moduleAugmentationGlobal4.symbols b/tests/baselines/reference/moduleAugmentationGlobal4.symbols
new file mode 100644
index 00000000000..f9cdac3fc2e
--- /dev/null
+++ b/tests/baselines/reference/moduleAugmentationGlobal4.symbols
@@ -0,0 +1,26 @@
+=== tests/cases/compiler/f1.ts ===
+
+declare global {
+>global : Symbol(, Decl(f1.ts, 0, 0))
+
+    interface Something {x}
+>Something : Symbol(Something, Decl(f1.ts, 1, 16), Decl(f2.ts, 1, 16))
+>x : Symbol(Something.x, Decl(f1.ts, 2, 25))
+}
+export {};
+=== tests/cases/compiler/f2.ts ===
+
+declare global {
+>global : Symbol(, Decl(f2.ts, 0, 0))
+
+    interface Something {y}
+>Something : Symbol(Something, Decl(f1.ts, 1, 16), Decl(f2.ts, 1, 16))
+>y : Symbol(Something.y, Decl(f2.ts, 2, 25))
+}
+export {};
+=== tests/cases/compiler/f3.ts ===
+import "./f1";
+No type information for this code.import "./f2";
+No type information for this code.
+No type information for this code.
+No type information for this code.
\ No newline at end of file
diff --git a/tests/baselines/reference/moduleAugmentationGlobal4.types b/tests/baselines/reference/moduleAugmentationGlobal4.types
new file mode 100644
index 00000000000..e3e780d69ff
--- /dev/null
+++ b/tests/baselines/reference/moduleAugmentationGlobal4.types
@@ -0,0 +1,26 @@
+=== tests/cases/compiler/f1.ts ===
+
+declare global {
+>global : any
+
+    interface Something {x}
+>Something : Something
+>x : any
+}
+export {};
+=== tests/cases/compiler/f2.ts ===
+
+declare global {
+>global : any
+
+    interface Something {y}
+>Something : Something
+>y : any
+}
+export {};
+=== tests/cases/compiler/f3.ts ===
+import "./f1";
+No type information for this code.import "./f2";
+No type information for this code.
+No type information for this code.
+No type information for this code.
\ No newline at end of file
diff --git a/tests/baselines/reference/moduleAugmentationGlobal5.errors.txt b/tests/baselines/reference/moduleAugmentationGlobal5.errors.txt
deleted file mode 100644
index 4f1f9133760..00000000000
--- a/tests/baselines/reference/moduleAugmentationGlobal5.errors.txt
+++ /dev/null
@@ -1,28 +0,0 @@
-tests/cases/compiler/f1.d.ts(4,19): error TS2665: Module augmentation cannot introduce new names in the top level scope.
-tests/cases/compiler/f2.d.ts(3,19): error TS2665: Module augmentation cannot introduce new names in the top level scope.
-
-
-==== tests/cases/compiler/f3.ts (0 errors) ====
-    /// <reference path="f1.d.ts"/>
-    /// <reference path="f2.d.ts"/>
-    import "A";
-    import "B";
-    
-    
-==== tests/cases/compiler/f1.d.ts (1 errors) ====
-    
-    declare module "A" {
-        global {
-            interface Something {x}
-                      ~~~~~~~~~
-!!! error TS2665: Module augmentation cannot introduce new names in the top level scope.
-        }
-    }
-==== tests/cases/compiler/f2.d.ts (1 errors) ====
-    declare module "B" {
-        global {
-            interface Something {y}
-                      ~~~~~~~~~
-!!! error TS2665: Module augmentation cannot introduce new names in the top level scope.
-        }
-    }
\ No newline at end of file
diff --git a/tests/baselines/reference/moduleAugmentationGlobal5.symbols b/tests/baselines/reference/moduleAugmentationGlobal5.symbols
new file mode 100644
index 00000000000..27548b05ef2
--- /dev/null
+++ b/tests/baselines/reference/moduleAugmentationGlobal5.symbols
@@ -0,0 +1,28 @@
+=== tests/cases/compiler/f3.ts ===
+/// <reference path="f1.d.ts"/>
+No type information for this code./// <reference path="f2.d.ts"/>
+No type information for this code.import "A";
+No type information for this code.import "B";
+No type information for this code.
+No type information for this code.
+No type information for this code.=== tests/cases/compiler/f1.d.ts ===
+
+declare module "A" {
+    global {
+>global : Symbol(, Decl(f1.d.ts, 1, 20))
+
+        interface Something {x}
+>Something : Symbol(Something, Decl(f1.d.ts, 2, 12), Decl(f2.d.ts, 1, 12))
+>x : Symbol(Something.x, Decl(f1.d.ts, 3, 29))
+    }
+}
+=== tests/cases/compiler/f2.d.ts ===
+declare module "B" {
+    global {
+>global : Symbol(, Decl(f2.d.ts, 0, 20))
+
+        interface Something {y}
+>Something : Symbol(Something, Decl(f1.d.ts, 2, 12), Decl(f2.d.ts, 1, 12))
+>y : Symbol(Something.y, Decl(f2.d.ts, 2, 29))
+    }
+}
diff --git a/tests/baselines/reference/moduleAugmentationGlobal5.types b/tests/baselines/reference/moduleAugmentationGlobal5.types
new file mode 100644
index 00000000000..b2e6139eb26
--- /dev/null
+++ b/tests/baselines/reference/moduleAugmentationGlobal5.types
@@ -0,0 +1,28 @@
+=== tests/cases/compiler/f3.ts ===
+/// <reference path="f1.d.ts"/>
+No type information for this code./// <reference path="f2.d.ts"/>
+No type information for this code.import "A";
+No type information for this code.import "B";
+No type information for this code.
+No type information for this code.
+No type information for this code.=== tests/cases/compiler/f1.d.ts ===
+
+declare module "A" {
+    global {
+>global : any
+
+        interface Something {x}
+>Something : Something
+>x : any
+    }
+}
+=== tests/cases/compiler/f2.d.ts ===
+declare module "B" {
+    global {
+>global : any
+
+        interface Something {y}
+>Something : Something
+>y : any
+    }
+}
diff --git a/tests/baselines/reference/newNamesInGlobalAugmentations1.js b/tests/baselines/reference/newNamesInGlobalAugmentations1.js
new file mode 100644
index 00000000000..5dc04f2f4aa
--- /dev/null
+++ b/tests/baselines/reference/newNamesInGlobalAugmentations1.js
@@ -0,0 +1,22 @@
+//// [tests/cases/compiler/newNamesInGlobalAugmentations1.ts] ////
+
+//// [f1.d.ts]
+
+export {};
+
+declare global {
+    interface SymbolConstructor {
+        observable: symbol;
+    }
+    class Cls {x}
+    let [a, b]: number[];
+}
+
+//// [main.ts]
+
+Symbol.observable;
+new Cls().x
+
+//// [main.js]
+Symbol.observable;
+new Cls().x;
diff --git a/tests/baselines/reference/newNamesInGlobalAugmentations1.symbols b/tests/baselines/reference/newNamesInGlobalAugmentations1.symbols
new file mode 100644
index 00000000000..be8ec6aa14d
--- /dev/null
+++ b/tests/baselines/reference/newNamesInGlobalAugmentations1.symbols
@@ -0,0 +1,34 @@
+=== tests/cases/compiler/f1.d.ts ===
+
+export {};
+
+declare global {
+>global : Symbol(, Decl(f1.d.ts, 1, 10))
+
+    interface SymbolConstructor {
+>SymbolConstructor : Symbol(SymbolConstructor, Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2015.symbol.d.ts, --, --), Decl(f1.d.ts, 3, 16))
+
+        observable: symbol;
+>observable : Symbol(SymbolConstructor.observable, Decl(f1.d.ts, 4, 33))
+    }
+    class Cls {x}
+>Cls : Symbol(Cls, Decl(f1.d.ts, 6, 5))
+>x : Symbol(Cls.x, Decl(f1.d.ts, 7, 15))
+
+    let [a, b]: number[];
+>a : Symbol(a, Decl(f1.d.ts, 8, 9))
+>b : Symbol(b, Decl(f1.d.ts, 8, 11))
+}
+
+=== tests/cases/compiler/main.ts ===
+
+Symbol.observable;
+>Symbol.observable : Symbol(SymbolConstructor.observable, Decl(f1.d.ts, 4, 33))
+>Symbol : Symbol(Symbol, Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2015.symbol.d.ts, --, --), Decl(lib.es2015.symbol.d.ts, --, --))
+>observable : Symbol(SymbolConstructor.observable, Decl(f1.d.ts, 4, 33))
+
+new Cls().x
+>new Cls().x : Symbol(Cls.x, Decl(f1.d.ts, 7, 15))
+>Cls : Symbol(Cls, Decl(f1.d.ts, 6, 5))
+>x : Symbol(Cls.x, Decl(f1.d.ts, 7, 15))
+
diff --git a/tests/baselines/reference/newNamesInGlobalAugmentations1.types b/tests/baselines/reference/newNamesInGlobalAugmentations1.types
new file mode 100644
index 00000000000..8d5baf19d08
--- /dev/null
+++ b/tests/baselines/reference/newNamesInGlobalAugmentations1.types
@@ -0,0 +1,35 @@
+=== tests/cases/compiler/f1.d.ts ===
+
+export {};
+
+declare global {
+>global : any
+
+    interface SymbolConstructor {
+>SymbolConstructor : SymbolConstructor
+
+        observable: symbol;
+>observable : symbol
+    }
+    class Cls {x}
+>Cls : Cls
+>x : any
+
+    let [a, b]: number[];
+>a : number
+>b : number
+}
+
+=== tests/cases/compiler/main.ts ===
+
+Symbol.observable;
+>Symbol.observable : symbol
+>Symbol : SymbolConstructor
+>observable : symbol
+
+new Cls().x
+>new Cls().x : any
+>new Cls() : Cls
+>Cls : typeof Cls
+>x : any
+
diff --git a/tests/cases/compiler/newNamesInGlobalAugmentations1.ts b/tests/cases/compiler/newNamesInGlobalAugmentations1.ts
new file mode 100644
index 00000000000..78cd1ec5c13
--- /dev/null
+++ b/tests/cases/compiler/newNamesInGlobalAugmentations1.ts
@@ -0,0 +1,17 @@
+// @target: es6
+
+// @filename: f1.d.ts
+export {};
+
+declare global {
+    interface SymbolConstructor {
+        observable: symbol;
+    }
+    class Cls {x}
+    let [a, b]: number[];
+}
+
+// @filename: main.ts
+
+Symbol.observable;
+new Cls().x
\ No newline at end of file