What causes "Invalid increment specification: {vals[1]}" in kovidgoyal/kitty?

Use a plain integer for the increment, e.g. `resize_window wider 3`

Invalid increment specification: {vals[1]}

Error message

Invalid increment specification: {vals[1]}

What it means

The second argument to resize_window could not be parsed as an integer; kitty keeps the default increment of 1.

Source

Thrown at kitty/options/utils.py:310


@func_with_args('resize_window')
def resize_window(func: str, rest: str) -> FuncArgsType:
    vals = rest.strip().split(maxsplit=1)
    if len(vals) > 2:
        log_error('resize_window needs one or two arguments, using defaults')
        args = ['wider', 1]
    else:
        quality = vals[0].lower()
        if quality not in ('reset', 'taller', 'shorter', 'wider', 'narrower'):
            log_error(f'Invalid quality specification: {quality}')
            quality = 'wider'
        increment = 1
        if len(vals) == 2:
            try:
                increment = int(vals[1])
            except Exception:
                log_error(f'Invalid increment specification: {vals[1]}')
        args = [quality, increment]
    return func, args


@func_with_args('move_window')
def move_window(func: str, rest: str) -> FuncArgsType:
    rest = rest.lower()
    rest = {'up': 'top', 'down': 'bottom'}.get(rest, rest)
    prest: int | str = rest
    try:
        prest = int(prest)
    except Exception:
        if prest not in ('left', 'right', 'top', 'bottom'):
            log_error(f'Invalid move_window specification: {rest}')
            prest = 0
    return func, [prest]

View on GitHub (pinned to 6d5d0c4406)

Solutions

Use a plain integer for the increment, e.g. `resize_window wider 3`
Strip any unit suffixes from the number

Example fix

# before
map f1 resize_window wider 2px
# after
map f1 resize_window wider 2

Defensive patterns

Strategy: validation

Validate before calling

ok = '2'.lstrip('+-').isdigit()

Prevention

Increment must be a bare integer
Avoid unit suffixes like px/lines

When it happens

Trigger: `map f1 resize_window wider two` — int(vals[1]) raises ValueError, the message reports the offending token.

Common situations: Writing the increment as a word, or including a unit/type suffix like '2px' or '3 rows'.

Understand the failure class

Background: "Invalid value" and "allowed values are" config errors: what your library rejected and how to fix it — this error's family across 41 libraries.

Related errors

AI-assisted analysis of kovidgoyal/kitty@6d5d0c4406 (2026-08-27). Data as JSON: /api/errors/ce3d260d505dfb46. Report an issue: GitHub.