diff --git a/src/parseTools.js b/src/parseTools.js
index 73d7e6472..a0bcf44f2 100644
--- a/src/parseTools.js
+++ b/src/parseTools.js
@@ -1118,12 +1118,20 @@ function makeSignOp(value, type, op) {
   }
   if (!correctSigns() && !CHECK_SIGNS) return value;
   if (type in Runtime.INT_TYPES) {
-    // shortcuts for 32-bit case
-    if (bits === 32 && !CHECK_SIGNS) {
-      if (op === 're') {
-        return '((' + value + ')|0)';
-      } else {
-        return '((' + value + ')>>>0)';
+    // shortcuts
+    if (!CHECK_SIGNS) {
+      if (bits === 32) {
+        if (op === 're') {
+          return '((' + value + ')|0)';
+        } else {
+          return '((' + value + ')>>>0)';
+        }
+      } else if (bits < 32) {
+        if (op === 'un') {
+          return '((' + value + ')&' + (Math.pow(2, bits)-1) + ')';
+        } else {
+          return '(tempInt=(' + value + '),(tempInt>=' + Math.pow(2, bits-1) + '?tempInt-' + Math.pow(2, bits) + ':tempInt))';
+        }
       }
     }
     return full;
@@ -1178,7 +1186,7 @@ function processMathop(item) { with(item) {
   var bitsLeft = ident2 ? ident2.substr(2, ident2.length-3) : null; // remove (i and ), to leave number. This value is important in float ops
 
   function integerizeBignum(value) {
-    return '(tempNumber=(' + value + '), tempNumber-tempNumber%1)';
+    return '(tempBigInt=(' + value + '), tempBigInt-tempBigInt%1)';
   }
 
   switch (op) {
diff --git a/src/preamble.js b/src/preamble.js
index c045bb2d1..8c2a9dcb9 100644
--- a/src/preamble.js
+++ b/src/preamble.js
@@ -288,8 +288,7 @@ var __ATEXIT__ = [];
 var ABORT = false;
 
 var undef = 0;
-var tempValue;
-var tempNumber;
+var tempValue, tempInt, tempBigInt;
 
 function abort(text) {
   print(text + ':\n' + (new Error).stack);
diff --git a/tests/runner.py b/tests/runner.py
index 18f9e9d89..4c7be5ff4 100644
--- a/tests/runner.py
+++ b/tests/runner.py
@@ -3095,7 +3095,6 @@ if 'benchmark' not in str(sys.argv):
 
       global CORRECT_SIGNS; CORRECT_SIGNS = 2
       global CORRECT_SIGNS_LINES; CORRECT_SIGNS_LINES = auto_optimize_data['signs_lines']
-      # TODO: Fast unSign for 8-bit values!
       global CORRECT_OVERFLOWS; CORRECT_OVERFLOWS = 0
       global CORRECT_ROUNDINGS; CORRECT_ROUNDINGS = 0
       global SAFE_HEAP; SAFE_HEAP = 0 # uses time.h to set random bytes, other stuff