diff --git a/src/dexorder/blockstate/blockdata.py b/src/dexorder/blockstate/blockdata.py
index eaf8a62..94684a1 100644
--- a/src/dexorder/blockstate/blockdata.py
+++ b/src/dexorder/blockstate/blockdata.py
@@ -71,8 +71,8 @@ class BlockData:
             raise KeyError
         return result
 
-    def delitem(self, item, overwrite=True):
-        self.setitem(item, DELETE, overwrite)
+    def delitem(self, item):
+        self.setitem(item, DELETE)
 
     def unload(self, item):
         """
@@ -134,7 +134,7 @@ class BlockSet(Generic[T], Iterable[T], BlockData):
         self.setitem(item, None, overwrite=False)
 
     def remove(self, item: T):
-        self.delitem(item, overwrite=False)
+        self.delitem(item)
 
     def __contains__(self, item: T) -> bool:
         return self.contains(item)
@@ -172,6 +172,9 @@ class BlockDict(Generic[K,V], BlockData):
     def get(self, item: K, default: V = None) -> V:
         return self.getitem(item, default)
 
+    def setdefault(self, item: K, value: V):
+        return self.setitem(item, value, overwrite=False)
+
     def modify(self, item: K, func: Callable[[V],V], default: V=NARG) -> V:
         result = func(self.getitem(item, default))
         self.setitem(item, result)
diff --git a/src/dexorder/blockstate/state.py b/src/dexorder/blockstate/state.py
index 9ed60e2..12e28ae 100644
--- a/src/dexorder/blockstate/state.py
+++ b/src/dexorder/blockstate/state.py
@@ -139,7 +139,7 @@ class BlockState:
 
     def set(self, fork: Optional[Fork], series, key, value, overwrite=True):
         diffs = self.diffs_by_series[series][key]
-        if overwrite or self._get_from_diffs(fork, diffs) != value:
+        if overwrite or self._get_from_diffs(fork, diffs) is DELETE and value is not DELETE:
             diff = DiffEntry(value,
                              fork.height if fork is not None else self.root_block.height,
                              fork.hash if fork is not None else self.root_block.hash)