diff --git a/acorn.js b/acorn.js
index 176920400f..1c7ec8f662 100644
--- a/acorn.js
+++ b/acorn.js
@@ -895,8 +895,8 @@
   var node_loc_t = function(s) {
     this.start=tokStartLoc;
     this.end=null;
+    if (sourceFile !== null) this.source=sourceFile;
   };
-  node_loc_t.prototype.source=sourceFile;
 
   function startNode() {
     var node = new node_t();
diff --git a/test/tests.js b/test/tests.js
index 5bd87c2be8..247decceab 100644
--- a/test/tests.js
+++ b/test/tests.js
@@ -26065,6 +26065,100 @@ test("foo: 10; foo: 20;", {
   ]
 });
 
+// option tests
+
+test("var a = 1;", {
+  "type": "Program",
+  "start": 0,
+  "end": 10,
+  "loc": {
+    "start": {
+      "line": 1,
+      "column": 0
+    },
+    "end": {
+      "line": 1,
+      "column": 10
+    },
+    "source": "test.js"
+  },
+  "body": [
+    {
+      "type": "VariableDeclaration",
+      "start": 0,
+      "end": 9,
+      "loc": {
+        "start": {
+          "line": 1,
+          "column": 0
+        },
+        "end": {
+          "line": 1,
+          "column": 9
+        },
+        "source": "test.js"
+      },
+      "declarations": [
+        {
+          "type": "VariableDeclarator",
+          "start": 4,
+          "end": 9,
+          "loc": {
+            "start": {
+              "line": 1,
+              "column": 4
+            },
+            "end": {
+              "line": 1,
+              "column": 9
+            },
+            "source": "test.js"
+          },
+          "id": {
+            "type": "Identifier",
+            "start": 4,
+            "end": 5,
+            "loc": {
+              "start": {
+                "line": 1,
+                "column": 4
+              },
+              "end": {
+                "line": 1,
+                "column": 5
+              },
+              "source": "test.js"
+            },
+            "name": "a"
+          },
+          "init": {
+            "type": "Literal",
+            "start": 8,
+            "end": 9,
+            "loc": {
+              "start": {
+                "line": 1,
+                "column": 8
+              },
+              "end": {
+                "line": 1,
+                "column": 9
+              },
+              "source": "test.js"
+            },
+            "value": 1,
+            "raw": "1"
+          }
+        }
+      ],
+      "kind": "var"
+    }
+  ]
+}, {
+  locations: true,
+  sourceFile: "test.js"
+})
+
 // Failure tests
 
 testFail("{",