diff --git a/httpie/cli.py b/httpie/cli.py
index 229ac274..b087f783 100644
--- a/httpie/cli.py
+++ b/httpie/cli.py
@@ -18,8 +18,8 @@ from .input import (Parser, AuthCredentialsArgType, KeyValueArgType,
                     SEP_PROXY, SEP_CREDENTIALS, SEP_GROUP_ALL_ITEMS,
                     OUT_REQ_HEAD, OUT_REQ_BODY, OUT_RESP_HEAD,
                     OUT_RESP_BODY, OUTPUT_OPTIONS, OUTPUT_OPTIONS_DEFAULT,
-                    PRETTY_MAP, PRETTY_STDOUT_TTY_ONLY, SessionNameValidator)
-from .utils import existing_file
+                    PRETTY_MAP, PRETTY_STDOUT_TTY_ONLY, SessionNameValidator,
+                    readable_file_arg)
 
 
 class HTTPieHelpFormatter(RawDescriptionHelpFormatter):
@@ -469,7 +469,7 @@ network.add_argument(
 network.add_argument(
     '--ssl-cert',
     default=None,
-    type=existing_file,
+    type=readable_file_arg,
     help="""
     You can specify a local cert to use as client side SSL certificate.
     This file may either contain both private key and certificate or you may
@@ -481,7 +481,7 @@ network.add_argument(
 network.add_argument(
     '--ssl-key',
     default=None,
-    type=existing_file,
+    type=readable_file_arg,
     help="""
     The private key to use with SSL. Only needed if --ssl-cert is given and the
     certificate file does not contain the private key.
diff --git a/httpie/input.py b/httpie/input.py
index 3c180129..24269db4 100644
--- a/httpie/input.py
+++ b/httpie/input.py
@@ -1,6 +1,7 @@
 """Parsing and processing of CLI input (args, auth credentials, files, stdin).
 
 """
+import argparse
 import os
 import sys
 import re
@@ -630,3 +631,12 @@ def parse_items(items, data=None, headers=None, files=None, params=None):
         target[item.key] = value
 
     return headers, data, files, params
+
+
+def readable_file_arg(filename):
+    try:
+        open(filename, 'rb')
+    except IOError as ex:
+        raise argparse.ArgumentTypeError(
+            '%s: %s' % (filename, ex.args[1]))
+    return filename
diff --git a/httpie/utils.py b/httpie/utils.py
index 3200cce2..37ac745d 100644
--- a/httpie/utils.py
+++ b/httpie/utils.py
@@ -1,5 +1,4 @@
 from __future__ import division
-import argparse
 
 
 def humanize_bytes(n, precision=2):
@@ -46,11 +45,3 @@ def humanize_bytes(n, precision=2):
 
     return '%.*f %s' % (precision, n / factor, suffix)
 
-
-def existing_file(filename):
-    try:
-        open(filename, 'rb')
-    except IOError as ex:
-        raise argparse.ArgumentTypeError(
-            '%s: %s' % (filename, ex.args[1]))
-    return filename