diff --git a/docs/guides/using-the-parser.md b/docs/guides/using-the-parser.md
index b564d0c..465fc50 100644
--- a/docs/guides/using-the-parser.md
+++ b/docs/guides/using-the-parser.md
@@ -12,7 +12,8 @@ parser.parse("abcd"); // throws an exception
 
 You can tweak parser behavior by passing a second parameter with an `options` object to the `parse` method. The following options are supported:
 
-  * `startRule` — name of the rule to start parsing from (depends on the rules the grammar supports as starting rules)
-  * `tracer` — tracer to use (only if the parser was generated with `"trace": true` option passed to the compiler)
+* `filename` — the name of the source passed to the generated parser; will be used by the `location()` helper
+* `startRule` — name of the rule to start parsing from (depends on the rules the grammar supports as starting rules)
+* `tracer` — tracer to use (only if the parser was generated with `"trace": true` option passed to the compiler)
 
 Parsers can also support their own custom options on the `options` object passed to them.
diff --git a/packages/pegjs/typings/generated-parser.d.ts b/packages/pegjs/typings/generated-parser.d.ts
index 8e8840c..581aec3 100644
--- a/packages/pegjs/typings/generated-parser.d.ts
+++ b/packages/pegjs/typings/generated-parser.d.ts
@@ -18,6 +18,7 @@ declare namespace generatedparser {
      */
     interface SourceLocation {
 
+        filename?: string;
         start: SourcePosition;
         end: SourcePosition;