diff --git a/u7/hash_table.py b/u7/hash_table.py
index cd10e66..17ad8e0 100644
--- a/u7/hash_table.py
+++ b/u7/hash_table.py
@@ -72,9 +72,10 @@ class HashTable:
 
     def __delitem__(self, key):
         index = self.probe(key)
-        if self.table[index] is not self.empty:
-            self.table[index] = self.deleted
-            self.size -= 1
+        if self.table[index] is self.empty or self.table[index] is self.deleted:
+            raise KeyError(key)
+        self.table[index] = self.deleted
+        self.size -= 1
 
     def __contains__(self, key):
         if self.table[self.probe(key)] is self.empty or self.table[self.probe(key)] is self.deleted:
@@ -87,5 +88,5 @@ class HashTable:
 
     def __iter__(self):
         for bucket in self.table:
-            if bucket is not self.empty:
+            if bucket is not self.empty and bucket is not self.deleted:
                 yield bucket[0]