--- xnu/xnu-4903.221.2/libkern/c++/OSData.cpp
+++ xnu/xnu-4570.71.2/libkern/c++/OSData.cpp
@@ -289,9 +289,7 @@
     if (capacity == EXTERNAL)
         return false;
     
-    if (os_add_overflow(length, inLength, &newSize))
-        return false;
-
+    newSize = length + inLength;
     if ( (newSize > capacity) && newSize > ensureCapacity(newSize) )
         return false;
 
@@ -315,9 +313,7 @@
     if (capacity == EXTERNAL)
         return false;
     
-    if (os_add_overflow(length, inLength, &newSize))
-        return false;
-
+    newSize = length + inLength;
     if ( (newSize > capacity) && newSize > ensureCapacity(newSize) )
         return false;