diff --git a/Lib/test/test_zlib.py b/Lib/test/test_zlib.py
index 88815160f8b..35bca884320 100644
--- a/Lib/test/test_zlib.py
+++ b/Lib/test/test_zlib.py
@@ -41,6 +41,12 @@ buf = buf * 16
 co = zlib.compressobj(8, 8, -15)
 x1 = co.compress(buf)
 x2 = co.flush()
+try:
+    co.flush()
+    print "Oops - second flush worked when it should not have!"
+except zlib.error:
+    pass
+
 x = x1 + x2
 
 dc = zlib.decompressobj(-15)
diff --git a/Modules/zlibmodule.c b/Modules/zlibmodule.c
index 8fc3bc20fdd..a3891f71336 100644
--- a/Modules/zlibmodule.c
+++ b/Modules/zlibmodule.c
@@ -648,6 +648,7 @@ PyZlib_flush(compobject *self, PyObject *args)
 	zlib_error(self->zst, err, "while flushing");
 	Py_DECREF(RetVal);
 	RetVal = NULL;
+	goto error;
     }
 
     if (_PyString_Resize(&RetVal, self->zst.total_out - start_total_out) < 0)