diff --git a/memcache.py b/memcache.py
index 3e6bd67..673db39 100644
--- a/memcache.py
+++ b/memcache.py
@@ -898,6 +898,7 @@ def set_multi(self, mapping, time=0, key_prefix='', min_compress_len=0,
         # send out all requests on each server before reading anything
         dead_servers = []
         notstored = []  # original keys.
+        has_valid_content = False
 
         for server in six.iterkeys(server_keys):
             bigcmd = []
@@ -914,6 +915,7 @@ def set_multi(self, mapping, time=0, key_prefix='', min_compress_len=0,
                                                    noreply,
                                                    b'\r\n', val, b'\r\n')
                         write(fullcmd)
+                        has_valid_content = True
                     else:
                         notstored.append(prefixed_to_orig_key[key])
                 server.send_cmds(b''.join(bigcmd))
@@ -927,6 +929,9 @@ def set_multi(self, mapping, time=0, key_prefix='', min_compress_len=0,
         if noreply:
             return notstored
 
+        if not has_valid_content:
+            return mapping.keys()
+
         # if any servers died on the way, don't expect them to respond.
         for server in dead_servers:
             del server_keys[server]