diff --git a/src/util.js b/src/util.js
index 78394ad4..f2d8bdef 100644
--- a/src/util.js
+++ b/src/util.js
@@ -85,12 +85,9 @@ export default {
 
   readNumber: function (bytes) {
     var n = 0;
-
     for (var i = 0; i < bytes.length; i++) {
-      n <<= 8;
-      n += bytes[i];
+      n += Math.pow(256, i) * bytes[bytes.length - 1 - i];
     }
-
     return n;
   },
 
diff --git a/test/general/util.js b/test/general/util.js
index d805eef1..06d75bb6 100644
--- a/test/general/util.js
+++ b/test/general/util.js
@@ -185,6 +185,12 @@ describe('Util unit tests', function() {
       var test = openpgp.util.decode_utf8.bind(null, {chameleon: true});
       expect(test).to.throw(Error, /Parameter "utf8" is not of type string/);
     });
+    it('util.readNumber should not overflow until full range of uint32', function () {
+      var ints = [Math.pow(2, 20), Math.pow(2, 25), Math.pow(2, 30), Math.pow(2, 32) - 1];
+      for(var i = 0; i < ints.length; i++) {
+        expect(openpgp.util.readNumber(openpgp.util.writeNumber(ints[i], 4))).to.equal(ints[i]);
+      }
+    });
   });
 
 });