diff --git a/contracts/util/safety.sol b/contracts/util/safety.sol
index 93d447c..5f4a2a0 100644
--- a/contracts/util/safety.sol
+++ b/contracts/util/safety.sol
@@ -1,6 +1,6 @@
 contract DSSafeAddSub {
     function safeToAdd(uint a, uint b) internal returns (bool) {
-        return (a + b > a);
+        return (a + b >= a);
     }
     function safeAdd(uint a, uint b) internal returns (uint) {
         if (!safeToAdd(a, b)) throw;
diff --git a/contracts/util/safety_test.sol b/contracts/util/safety_test.sol
new file mode 100644
index 0000000..24e2c8e
--- /dev/null
+++ b/contracts/util/safety_test.sol
@@ -0,0 +1,10 @@
+import 'dapple/test.sol';
+import 'util/safety.sol';
+
+contract SafeAddSubTest is Test, DSSafeAddSub {
+    function setUp() {
+    }
+    function testSafeToAddFix() {
+        assertTrue(safeToAdd(1, 0));
+    }
+}
diff --git a/dappfile b/dappfile
index 815ac97..d405442 100644
--- a/dappfile
+++ b/dappfile
@@ -1,5 +1,5 @@
 name: dappsys
-version: 0.1.0
+version: 0.1.1
 layout:
   sol_sources: contracts
   build_dir: build