diff --git a/httpie/cli/definition.py b/httpie/cli/definition.py
index 3d5650c007..f18d8e35ee 100644
--- a/httpie/cli/definition.py
+++ b/httpie/cli/definition.py
@@ -66,8 +66,8 @@
         $ http example.org hello=world   # => POST
 
     """,
-).completer = ChoicesCompleter(
-    ('GET', 'HEAD', 'POST', 'PUT', 'PATCH', 'DELETE', 'OPTIONS'))
+    completer=ChoicesCompleter(('GET', 'HEAD', 'POST', 'PUT', 'PATCH', 'DELETE', 'OPTIONS'))
+)
 positional_arguments.add_argument(
     dest='url',
     metavar='URL',
@@ -82,7 +82,8 @@
         $ http :/foo                    # => http://localhost/foo
 
     """,
-).completer = ChoicesCompleter(())
+    completer=ChoicesCompleter(()),
+)
 positional_arguments.add_argument(
     dest='request_items',
     metavar='REQUEST_ITEM',
@@ -139,7 +140,8 @@
         field-name-with\:colon=value
 
     """,
-).completer = ChoicesCompleter(())
+    completer=ChoicesCompleter(()),
+)
 
 #######################################################################
 # Content type.
@@ -192,8 +194,9 @@
     short_help=(
         'Specify a custom boundary string for multipart/form-data requests. '
         'Only has effect only together with --form.'
-    )
-).completer = ChoicesCompleter(())
+    ),
+    completer=ChoicesCompleter(()),
+)
 content_types.add_argument(
     '--raw',
     short_help='Pass raw request data without extra processing.',
@@ -354,7 +357,8 @@ def format_style_help(available_styles, *, isolation_mode: bool = False):
         --response-charset=big5
 
     """,
-).completer = ChoicesCompleter(())
+    completer=ChoicesCompleter(()),
+)
 output_processing.add_argument(
     '--response-mime',
     metavar='MIME_TYPE',
@@ -367,7 +371,8 @@ def format_style_help(available_styles, *, isolation_mode: bool = False):
         --response-mime=text/xml
 
     """,
-).completer = ChoicesCompleter(())
+    completer=ChoicesCompleter(()),
+)
 output_processing.add_argument(
     '--format-options',
     action='append',
@@ -392,7 +397,8 @@ def format_style_help(available_styles, *, isolation_mode: bool = False):
             f'        {option}' for option in DEFAULT_FORMAT_OPTIONS
         ).strip()
     ),
-).completer = ChoicesCompleter(())
+    completer=ChoicesCompleter(()),
+)
 
 #######################################################################
 # Output options
@@ -421,7 +427,8 @@ def format_style_help(available_styles, *, isolation_mode: bool = False):
     response body is printed by default.
 
     """,
-).completer = ChoicesCompleter(())
+    completer=ChoicesCompleter(()),
+)
 output_options.add_argument(
     '--headers',
     '-h',
@@ -495,7 +502,8 @@ def format_style_help(available_styles, *, isolation_mode: bool = False):
     dest='output_options_history',
     metavar='WHAT',
     help=Qualifiers.SUPPRESS,
-).completer = ChoicesCompleter(())
+    completer=ChoicesCompleter(()),
+)
 output_options.add_argument(
     '--stream',
     '-S',
@@ -529,7 +537,8 @@ def format_style_help(available_styles, *, isolation_mode: bool = False):
     printed to stderr.
 
     """,
-).completer = FilesCompleter()
+    completer=FilesCompleter(),
+)
 
 output_options.add_argument(
     '--download',
@@ -600,7 +609,8 @@ def format_style_help(available_styles, *, isolation_mode: bool = False):
 
         https://httpie.io/docs/cli/config-file-directory
     """,
-).completer = FilesCompleter(('json',))
+    completer=FilesCompleter(('json',)),
+)
 sessions.add_argument(
     '--session-read-only',
     metavar='SESSION_NAME_OR_PATH',
@@ -611,7 +621,8 @@ def format_style_help(available_styles, *, isolation_mode: bool = False):
     exchange.
 
     """,
-).completer = FilesCompleter(('json',))
+    completer=FilesCompleter(('json',)),
+)
 
 #######################################################################
 # Authentication
@@ -675,7 +686,8 @@ def format_auth_help(auth_plugins_mapping, *, isolation_mode: bool = False):
     (-a username), HTTPie will prompt for the password.
 
     """,
-).completer = ChoicesCompleter(())
+    completer=ChoicesCompleter(()),
+)
 authentication.add_argument(
     '--auth-type',
     '-A',
@@ -686,7 +698,8 @@ def format_auth_help(auth_plugins_mapping, *, isolation_mode: bool = False):
     cache=False,
     short_help='The authentication mechanism to be used.',
     help_formatter=format_auth_help,
-).completer = ChoicesCompleter(())
+    completer=ChoicesCompleter(()),
+)
 authentication.add_argument(
     '--ignore-netrc',
     default=False,
@@ -720,7 +733,8 @@ def format_auth_help(auth_plugins_mapping, *, isolation_mode: bool = False):
     and $HTTPS_proxy are supported as well.
 
     """,
-).completer = ChoicesCompleter(())
+    completer=ChoicesCompleter(()),
+)
 network.add_argument(
     '--follow',
     '-F',
@@ -738,7 +752,8 @@ def format_auth_help(auth_plugins_mapping, *, isolation_mode: bool = False):
     By default, requests have a limit of 30 redirects (works with --follow).
 
     """,
-).completer = ChoicesCompleter(())
+    completer=ChoicesCompleter(()),
+)
 network.add_argument(
     '--max-headers',
     type=int,
@@ -746,8 +761,9 @@ def format_auth_help(auth_plugins_mapping, *, isolation_mode: bool = False):
     short_help=(
         'The maximum number of response headers to be read before '
         'giving up (default 0, i.e., no limit).'
-    )
-).completer = ChoicesCompleter(())
+    ),
+    completer=ChoicesCompleter(()),
+)
 
 network.add_argument(
     '--timeout',
@@ -764,7 +780,8 @@ def format_auth_help(auth_plugins_mapping, *, isolation_mode: bool = False):
     the underlying socket for timeout seconds).
 
     """,
-).completer = ChoicesCompleter(())
+    completer=ChoicesCompleter(()),
+)
 network.add_argument(
     '--check-status',
     default=False,
@@ -814,7 +831,8 @@ def format_auth_help(auth_plugins_mapping, *, isolation_mode: bool = False):
     for private certs. (Or you can set the REQUESTS_CA_BUNDLE environment
     variable instead.)
     """,
-).completer = ChoicesCompleter(('yes', 'no'))
+    completer=ChoicesCompleter(('yes', 'no')),
+)
 ssl.add_argument(
     '--ssl',
     dest='ssl_version',
@@ -828,7 +846,8 @@ def format_auth_help(auth_plugins_mapping, *, isolation_mode: bool = False):
     are shown here).
 
     """,
-).completer = ChoicesCompleter(())
+    completer=ChoicesCompleter(()),
+)
 ssl.add_argument(
     '--ciphers',
     short_help='A string in the OpenSSL cipher list format.',
@@ -840,7 +859,8 @@ def format_auth_help(auth_plugins_mapping, *, isolation_mode: bool = False):
     {DEFAULT_SSL_CIPHERS}
 
     """,
-).completer = ChoicesCompleter(())
+    completer=ChoicesCompleter(()),
+)
 ssl.add_argument(
     '--cert',
     default=None,
@@ -852,7 +872,8 @@ def format_auth_help(auth_plugins_mapping, *, isolation_mode: bool = False):
     specify --cert-key separately.
 
     """,
-).completer = FilesCompleter(('crt', 'cert', 'pem'))
+    completer=FilesCompleter(('crt', 'cert', 'pem')),
+)
 ssl.add_argument(
     '--cert-key',
     default=None,
@@ -863,7 +884,8 @@ def format_auth_help(auth_plugins_mapping, *, isolation_mode: bool = False):
     certificate file does not contain the private key.
 
     """,
-).completer = FilesCompleter(('key', 'pem'))
+    completer=FilesCompleter(('key', 'pem')),
+)
 
 ssl.add_argument(
     '--cert-key-pass',
@@ -874,8 +896,9 @@ def format_auth_help(auth_plugins_mapping, *, isolation_mode: bool = False):
     The passphrase to be used to with the given private key. Only needed if --cert-key
     is given and the key file requires a passphrase.
     If not provided, you’ll be prompted interactively.
-    """
-).completer = ChoicesCompleter(())
+    """,
+    completer=ChoicesCompleter(()),
+)
 
 #######################################################################
 # Troubleshooting
@@ -916,8 +939,9 @@ def format_auth_help(auth_plugins_mapping, *, isolation_mode: bool = False):
 troubleshooting.add_argument(
     '--default-scheme',
     default='http',
-    short_help='The default scheme to use if not specified in the URL.'
-).completer = ChoicesCompleter(('http', 'https'))
+    short_help='The default scheme to use if not specified in the URL.',
+    completer=ChoicesCompleter(('http', 'https')),
+)
 troubleshooting.add_argument(
     '--debug',
     action='store_true',
diff --git a/httpie/cli/options.py b/httpie/cli/options.py
index c06a8ee615..3fe8ed7858 100644
--- a/httpie/cli/options.py
+++ b/httpie/cli/options.py
@@ -187,7 +187,7 @@ def __getattr__(self, attribute_name):
     Qualifiers.ZERO_OR_MORE: argparse.ZERO_OR_MORE,
     Qualifiers.ONE_OR_MORE: argparse.ONE_OR_MORE
 }
-ARGPARSE_IGNORE_KEYS = ('short_help', 'nested_options')
+ARGPARSE_IGNORE_KEYS = ('short_help', 'nested_options', 'completer')
 
 
 def to_argparse(
@@ -211,12 +211,14 @@ def to_argparse(
             concrete_group = concrete_group.add_mutually_exclusive_group(required=False)
 
         for abstract_argument in abstract_group.arguments:
-            concrete_group.add_argument(
+            argument = concrete_group.add_argument(
                 *abstract_argument.aliases,
                 **drop_keys(map_qualifiers(
                     abstract_argument.configuration, ARGPARSE_QUALIFIER_MAP
                 ), ARGPARSE_IGNORE_KEYS)
             )
+            if 'completer' in abstract_argument.configuration:
+                argument.completer = abstract_argument.configuration['completer']
 
     return concrete_parser