diff --git a/lib/rules/no-shadow.js b/lib/rules/no-shadow.js
index 18d2c2593ba8..9327269a9b1a 100644
--- a/lib/rules/no-shadow.js
+++ b/lib/rules/no-shadow.js
@@ -44,7 +44,8 @@ module.exports = {
         ],
 
         messages: {
-            noShadow: "'{{name}}' is already declared in the upper scope {{shadowedLine}}:{{shadowedColumn}}."
+            noShadow: "'{{name}}' is already declared in the upper scope {{shadowedLine}}:{{shadowedColumn}}.",
+            noShadowGlobal: "{{name}} is already a global variable."
         }
     },
 
@@ -128,13 +129,13 @@ module.exports = {
 
             if (identifier) {
                 obj = {
+                    global: false,
                     line: identifier.loc.start.line,
                     column: identifier.loc.start.column + 1
                 };
             } else {
                 obj = {
-                    line: 0,
-                    column: 0
+                    global: true
                 };
             }
             return obj;
@@ -189,12 +190,15 @@ module.exports = {
                     !(options.hoist !== "all" && isInTdz(variable, shadowed))
                 ) {
                     const location = getDeclaredLocation(shadowed);
+                    const messageId = location.global ? "noShadowGlobal" : "noShadow";
 
-                    variable.shadowedLine = location.line;
-                    variable.shadowedColumn = location.column;
+                    if (!location.global) {
+                        variable.shadowedLine = location.line;
+                        variable.shadowedColumn = location.column;
+                    }
                     context.report({
                         node: variable.identifiers[0],
-                        messageId: "noShadow",
+                        messageId,
                         data: variable
                     });
                 }
diff --git a/tests/lib/rules/no-shadow.js b/tests/lib/rules/no-shadow.js
index 2053c675f56c..dc2cc63c4dea 100644
--- a/tests/lib/rules/no-shadow.js
+++ b/tests/lib/rules/no-shadow.js
@@ -633,11 +633,9 @@ ruleTester.run("no-shadow", rule, {
             code: "function foo() { var Object = 0; }",
             options: [{ builtinGlobals: true }],
             errors: [{
-                messageId: "noShadow",
+                messageId: "noShadowGlobal",
                 data: {
-                    name: "Object",
-                    shadowedLine: 0,
-                    shadowedColumn: 0
+                    name: "Object"
                 },
                 type: "Identifier"
             }]
@@ -647,11 +645,9 @@ ruleTester.run("no-shadow", rule, {
             options: [{ builtinGlobals: true }],
             env: { browser: true },
             errors: [{
-                messageId: "noShadow",
+                messageId: "noShadowGlobal",
                 data: {
-                    name: "top",
-                    shadowedLine: 0,
-                    shadowedColumn: 0
+                    name: "top"
                 },
                 type: "Identifier"
             }]
@@ -661,11 +657,9 @@ ruleTester.run("no-shadow", rule, {
             options: [{ builtinGlobals: true }],
             parserOptions: { ecmaVersion: 6, sourceType: "module" },
             errors: [{
-                messageId: "noShadow",
+                messageId: "noShadowGlobal",
                 data: {
-                    name: "Object",
-                    shadowedLine: 0,
-                    shadowedColumn: 0
+                    name: "Object"
                 },
                 type: "Identifier"
             }]
@@ -676,11 +670,9 @@ ruleTester.run("no-shadow", rule, {
             parserOptions: { ecmaVersion: 6, sourceType: "module" },
             env: { browser: true },
             errors: [{
-                messageId: "noShadow",
+                messageId: "noShadowGlobal",
                 data: {
-                    name: "top",
-                    shadowedLine: 0,
-                    shadowedColumn: 0
+                    name: "top"
                 },
                 type: "Identifier"
             }]
@@ -690,11 +682,9 @@ ruleTester.run("no-shadow", rule, {
             options: [{ builtinGlobals: true }],
             parserOptions: { ecmaFeatures: { globalReturn: true } },
             errors: [{
-                messageId: "noShadow",
+                messageId: "noShadowGlobal",
                 data: {
-                    name: "Object",
-                    shadowedLine: 0,
-                    shadowedColumn: 0
+                    name: "Object"
                 },
                 type: "Identifier"
             }]
@@ -705,11 +695,9 @@ ruleTester.run("no-shadow", rule, {
             parserOptions: { ecmaFeatures: { globalReturn: true } },
             env: { browser: true },
             errors: [{
-                messageId: "noShadow",
+                messageId: "noShadowGlobal",
                 data: {
-                    name: "top",
-                    shadowedLine: 0,
-                    shadowedColumn: 0
+                    name: "top"
                 },
                 type: "Identifier"
             }]