1 files changed, 12 insertions, 4 deletions
diff --git a/Lib/os.py b/Lib/os.py
index 5f35f4c..12d80ee 100644
--- a/Lib/os.py
+++ b/Lib/os.py
@@ -644,7 +644,11 @@ class _Environ(MutableMapping):
         self._data = data
 
     def __getitem__(self, key):
-        value = self._data[self.encodekey(key)]
+        try:
+            value = self._data[self.encodekey(key)]
+        except KeyError:
+            # raise KeyError with the original key value
+            raise KeyError(key)
         return self.decodevalue(value)
 
     def __setitem__(self, key, value):
@@ -654,9 +658,13 @@ class _Environ(MutableMapping):
         self._data[key] = value
 
     def __delitem__(self, key):
-        key = self.encodekey(key)
-        self.unsetenv(key)
-        del self._data[key]
+        encodedkey = self.encodekey(key)
+        self.unsetenv(encodedkey)
+        try:
+            del self._data[encodedkey]
+        except KeyError:
+            # raise KeyError with the original key value
+            raise KeyError(key)
 
     def __iter__(self):
         for key in self._data: