diff --git a/ConflictSet.cpp b/ConflictSet.cpp
index 15814af..561c352 100644
--- a/ConflictSet.cpp
+++ b/ConflictSet.cpp
@@ -322,8 +322,7 @@ inline void Node3::copyChildrenAndKeyFrom(const Node0 &other) {
 inline void Node3::copyChildrenAndKeyFrom(const Node3 &other) {
   memcpy((char *)this + kNodeCopyBegin, (char *)&other + kNodeCopyBegin,
          kNodeCopySize);
-  memcpy(index, other.index,
-         sizeof(*this) - offsetof(Node3, index) + partialKeyLen);
+  memcpy(index, other.index, sizeof(*this) - sizeof(Node) + partialKeyLen);
   for (int i = 0; i < numChildren; ++i) {
     assert(children[i].child->parent == &other);
     children[i].child->parent = this;
@@ -409,7 +408,7 @@ inline void Node48::copyChildrenAndKeyFrom(const Node48 &other) {
   memcpy((char *)this + kNodeCopyBegin, (char *)&other + kNodeCopyBegin,
          kNodeCopySize);
   memcpy(&bitSet, &other.bitSet,
-         offsetof(Node48, children) - offsetof(Node48, bitSet));
+         sizeof(*this) - sizeof(Node) - sizeof(children));
   for (int i = 0; i < numChildren; ++i) {
     children[i] = other.children[i];
     assert(children[i].child->parent == &other);