diff --git a/05_sumAll/sumAll.js b/05_sumAll/sumAll.js
index 16f3de7..8ee567f 100644
--- a/05_sumAll/sumAll.js
+++ b/05_sumAll/sumAll.js
@@ -1,4 +1,7 @@
 const sumAll = function(a, b) {
+    if (a < 0 || b < 0) {
+        return "ERROR";
+    }
     let c, sum = 0;
     for ((a > b) ? (i = b, c = a)
                  : (i = a, c = b); i <= c; i++) {
diff --git a/05_sumAll/sumAll.spec.js b/05_sumAll/sumAll.spec.js
index 6c53087..7927aae 100644
--- a/05_sumAll/sumAll.spec.js
+++ b/05_sumAll/sumAll.spec.js
@@ -10,7 +10,7 @@ describe('sumAll', () => {
   test('works with larger number first', () => {
     expect(sumAll(123, 1)).toEqual(7626);
   });
-  test.skip('returns ERROR with negative numbers', () => {
+  test('returns ERROR with negative numbers', () => {
     expect(sumAll(-10, 4)).toEqual('ERROR');
   });
   test.skip('returns ERROR with non-number parameters', () => {