diff --git a/Lib/asynchat.py b/Lib/asynchat.py
index f1a5731..0cc91a8 100644
--- a/Lib/asynchat.py
+++ b/Lib/asynchat.py
@@ -181,6 +181,9 @@
         self.close()
 
     def push (self, data):
+        if not isinstance(data, (bytes, bytearray, memoryview)):
+            raise TypeError('data argument must be byte-ish (%r)',
+                            type(data))
         sabs = self.ac_out_buffer_size
         if len(data) > sabs:
             for i in range(0, len(data), sabs):