diff --git a/paramiko/pkey.py b/paramiko/pkey.py
index e1094794b52790b9ffe81cd0f3ff75a608226afa_cGFyYW1pa28vcGtleS5weQ==..d72bdd2323b2b53529df94ef1bab7c3e5c30163e_cGFyYW1pa28vcGtleS5weQ== 100644
--- a/paramiko/pkey.py
+++ b/paramiko/pkey.py
@@ -324,7 +324,9 @@
 
     def _read_private_key(self, tag, f, password=None):
         lines = f.readlines()
-
+        if not lines:
+            raise SSHException("no lines in {} private key file".format(tag))
+            
         # find the BEGIN tag
         start = 0
         m = self.BEGIN_TAG.match(lines[start])