diff --git a/calculator/calculator.app.js b/calculator/calculator.app.js
index df5f087..ab23c41 100644
--- a/calculator/calculator.app.js
+++ b/calculator/calculator.app.js
@@ -292,7 +292,9 @@ function displayOutput(num) {
     } else {
         num = numStr;
     }
-    num = num.replace("-","- "); // fix padding for '-'
+    if (num.charAt(0) === '-') {
+      num = '- ' + num.substr(1);
+    }
     g.setFont('7x11Numeric7Seg', 2);
     if (num.length > RESULT_MAX_LEN) {
       if (num.indexOf("E") < 0)