diff --git a/sumAll.js b/sumAll.js
index ea8276f..6893836 100644
--- a/sumAll.js
+++ b/sumAll.js
@@ -16,6 +16,11 @@ const sumAll = function(...args) {
         lastNumber = tempNumber;
     }
 
+    /*If either number is negative, return 'ERROR' */
+    if (firstNumber < 0 || lastNumber < 0) {
+        return 'ERROR';
+    }
+
     for (let i = firstNumber; i <= lastNumber; i++) {
         totalOfNumbers += i;
     }
diff --git a/sumAll.spec.js b/sumAll.spec.js
index f2a1052..15a6a91 100644
--- a/sumAll.spec.js
+++ b/sumAll.spec.js
@@ -10,7 +10,7 @@ describe('sumAll', function() {
     it('works with larger number first', function() {
         expect(sumAll(123, 1)).toEqual(7626);
     });
-    xit('returns ERROR with negative numbers', function() {
+    it('returns ERROR with negative numbers', function() {
         expect(sumAll(-10, 4)).toEqual('ERROR');
     });
     xit('returns ERROR with non-number parameters', function() {