diff --git a/src/services/completions.ts b/src/services/completions.ts
index 64ea05e4f2b..fb0e5226cf6 100644
--- a/src/services/completions.ts
+++ b/src/services/completions.ts
@@ -24,7 +24,7 @@ namespace ts.Completions {
         const entries: CompletionEntry[] = [];
 
         if (isSourceFileJavaScript(sourceFile)) {
-            const uniqueNames = getCompletionEntriesFromSymbols(symbols, entries, location, /*performCharacterChecks*/ false);
+            const uniqueNames = getCompletionEntriesFromSymbols(symbols, entries, location, /*performCharacterChecks*/ true);
             addRange(entries, getJavaScriptCompletionEntries(sourceFile, location.pos, uniqueNames));
         }
         else {
diff --git a/tests/cases/fourslash/completionListInvalidMemberNames3.ts b/tests/cases/fourslash/completionListInvalidMemberNames3.ts
new file mode 100644
index 00000000000..cf1141b4094
--- /dev/null
+++ b/tests/cases/fourslash/completionListInvalidMemberNames3.ts
@@ -0,0 +1,71 @@
+/// <reference path='fourslash.ts' />
+
+// @allowjs: true
+
+// @Filename: test.js
+////interface Symbol {
+////    /** Returns a string representation of an object. */
+////    toString(): string;
+
+////    /** Returns the primitive value of the specified object. */
+////    valueOf(): Object;
+////}
+
+////interface SymbolConstructor {
+////    /** 
+////      * A reference to the prototype. 
+////      */
+////    readonly prototype: Symbol;
+
+////    /**
+////      * Returns a new unique Symbol value.
+////      * @param  description Description of the new Symbol object.
+////      */
+////    (description?: string | number): symbol;
+
+////    /**
+////      * Returns a Symbol object from the global symbol registry matching the given key if found. 
+////      * Otherwise, returns a new symbol with this key.
+////      * @param key key to search for.
+////      */
+////    for(key: string): symbol;
+
+////    /**
+////      * Returns a key from the global symbol registry matching the given Symbol if found. 
+////      * Otherwise, returns a undefined.
+////      * @param sym Symbol to find the key for.
+////      */
+////    keyFor(sym: symbol): string | undefined;
+////}
+
+////declare var Symbol: SymbolConstructor;/// <reference path="lib.es2015.symbol.d.ts" />
+
+////interface SymbolConstructor {
+////    /** 
+////      * A method that determines if a constructor object recognizes an object as one of the 
+////      * constructor’s instances. Called by the semantics of the instanceof operator. 
+////      */
+////    readonly hasInstance: symbol;
+////}
+
+////interface Function {
+////    /**
+////     * Determines whether the given value inherits from this function if this function was used
+////     * as a constructor function.
+////     *
+////     * A constructor function can control which objects are recognized as its instances by
+////     * 'instanceof' by overriding this method.
+////     */
+////    [Symbol.hasInstance](value: any): boolean;
+////}
+
+////interface SomeInterface {
+////    (value: number): any;
+////}
+
+////var _ : SomeInterface;
+////_./**/
+
+goTo.marker();
+
+verify.not.completionListContains("[Symbol.hasInstance]");
\ No newline at end of file