diff --git a/src/eval.js b/src/eval.js
index 707003d..c058ab9 100644
--- a/src/eval.js
+++ b/src/eval.js
@@ -902,6 +902,8 @@ const do_eval_frame_expr = (node, scope, callsleft) => {
         value = !expr.result.value
       } else if(node.operator == 'typeof') {
         value = typeof(expr.result.value)
+      } else if(node.operator == '-') {
+        value = - expr.result.value
       } else {
         throw new Error('unknown op')
       }
diff --git a/src/parse_js.js b/src/parse_js.js
index cec0423..52aef70 100644
--- a/src/parse_js.js
+++ b/src/parse_js.js
@@ -101,7 +101,7 @@ const tokenize_js = (str) => {
                                         .join('|')},
     {name: 'keyword'            , re: reserved.map(r => '\\b' + r + '\\b').join('|')},
     // TODO all possible notatins for js numbers
-    {name: 'number'             , re: '-?\\d*\\.?\\d+'},
+    {name: 'number'             , re: '\\d*\\.?\\d+'},
     {name: 'identifier'         , re: '[A-Za-z_$][A-Za-z0-9_$]*'},
   
     {name: 'punctuation'        , 
@@ -1012,13 +1012,13 @@ const primary = if_fail(
 )
 
 // operator precedence https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Operator_Precedence
-// TODO unary minus
 // TODO instanceof
 const expr =
   [
     grouping,
     function_call_or_member_access,
     unary('!'),
+    unary('-'),
     unary('typeof'),
     binary(['**']),
     binary(['*','/','%']),
diff --git a/test/test.js b/test/test.js
index 06f883d..34a2b86 100644
--- a/test/test.js
+++ b/test/test.js
@@ -573,9 +573,10 @@ export const tests = [
     assert_code_evals_to('typeof 1', 'number')
   }),
 
-  test('eval_frame unary minus', () => {
-    // TODO
-    //assert_code_evals_to(`-(1)`, -1)
+  test_only('eval_frame unary minus', () => {
+    assert_code_evals_to(`-(1)`, -1)
+    assert_code_evals_to(`-1`, -1)
+    assert_code_evals_to(`-(-1)`, 1)
   }),
 
   test('eval_frame binary', () => {