diff --git a/Lib/ftplib.py b/Lib/ftplib.py
index 807bc383eeb..222e77d654d 100644
--- a/Lib/ftplib.py
+++ b/Lib/ftplib.py
@@ -221,7 +221,7 @@ class FTP:
     def voidresp(self):
         """Expect a response beginning with '2'."""
         resp = self.getresp()
-        if resp[0] != '2':
+        if resp[:1] != '2':
             raise error_reply, resp
         return resp
 
@@ -520,8 +520,6 @@ class FTP:
         resp = self.sendcmd('DELE ' + filename)
         if resp[:3] in ('250', '200'):
             return resp
-        elif resp[:1] == '5':
-            raise error_perm, resp
         else:
             raise error_reply, resp
 
diff --git a/Misc/NEWS b/Misc/NEWS
index 09190a0b900..c10896433f9 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -95,6 +95,8 @@ Core and Builtins
 Library
 -------
 
+- Issue 1726172: fix IndexError in the case of and empty response in ftplib.
+
 - Issue 2625: added missing iteritems() call to the for loop in
   mailbox.MH.get_message().