1 files changed, 11 insertions, 2 deletions
diff --git a/lib/abi.js b/lib/abi.js
index 13d6e45fc..8af10c382 100644
--- a/lib/abi.js
+++ b/lib/abi.js
@@ -175,7 +175,16 @@ var setupOutputTypes = function () {
     /// Formats input right-aligned input bytes to int
     /// @returns right-aligned input bytes formatted to int
     var formatInt = function (value) {
-        return value.length <= 8 ? +parseInt(value, 16) : hexToDec(value);
+        // check if it's negative number
+        // it it is, return two's complement
+        if (value.substr(0, 1).toLowerCase() === 'f') {
+            return new BigNumber(value, 16).minus(new BigNumber('ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff', 16)).minus(1);
+        }
+        return new BigNumber(value, 16);
+    };
+
+    var formatUInt = function (value) {
+        return new BigNumber(value, 16);
     };
 
     /// @returns right-aligned input bytes formatted to hex
@@ -199,7 +208,7 @@ var setupOutputTypes = function () {
     };
 
     return [
-        { type: prefixedType('uint'), format: formatInt },
+        { type: prefixedType('uint'), format: formatUInt },
         { type: prefixedType('int'), format: formatInt },
         { type: prefixedType('hash'), format: formatHash },
         { type: prefixedType('string'), format: formatString },