diff --git a/src/services/codefixes/fixImplicitThis.ts b/src/services/codefixes/fixImplicitThis.ts
index 743db5c7f35..a373c283052 100644
--- a/src/services/codefixes/fixImplicitThis.ts
+++ b/src/services/codefixes/fixImplicitThis.ts
@@ -4,7 +4,7 @@ namespace ts.codefix {
     const errorCodes = [Diagnostics.this_implicitly_has_type_any_because_it_does_not_have_a_type_annotation.code];
     registerCodeFix({
         errorCodes,
-        getCodeActions(context) {
+        getCodeActions: function getCodeActionsToFixImplicitThis(context) {
             const { sourceFile, program, span } = context;
             let diagnostic: DiagnosticAndArguments | undefined;
             const changes = textChanges.ChangeTracker.with(context, t => {
@@ -20,7 +20,7 @@ namespace ts.codefix {
 
     function doChange(changes: textChanges.ChangeTracker, sourceFile: SourceFile, pos: number, checker: TypeChecker): DiagnosticAndArguments | undefined {
         const token = getTokenAtPosition(sourceFile, pos);
-        Debug.assert(token.kind === SyntaxKind.ThisKeyword);
+        if (!isThis(token)) return undefined;
 
         const fn = getThisContainer(token, /*includeArrowFunctions*/ false);
         if (!isFunctionDeclaration(fn) && !isFunctionExpression(fn)) return undefined;
diff --git a/tests/cases/fourslash/codeFixImplicitThis_ts_functionDeclarationInGlobalScope.ts b/tests/cases/fourslash/codeFixImplicitThis_ts_functionDeclarationInGlobalScope.ts
new file mode 100644
index 00000000000..a2d51ba8611
--- /dev/null
+++ b/tests/cases/fourslash/codeFixImplicitThis_ts_functionDeclarationInGlobalScope.ts
@@ -0,0 +1,12 @@
+/// <reference path='fourslash.ts' />
+
+// @noImplicitThis: true
+
+////function foo() {
+////    let x: typeof /**/this;
+////}
+
+verify.codeFixAvailable([
+    { description: "Infer 'this' type of 'foo' from usage" },
+    { description: "Remove unused declaration for: 'x'" }
+]);