diff --git a/index.js b/index.js
index 8fb2728..b136421 100644
--- a/index.js
+++ b/index.js
@@ -35,6 +35,13 @@ export default function cliTruncate(text, columns, options = {}) {
 		throw new TypeError(`Expected \`columns\` to be a number, got ${typeof columns}`);
 	}
 
+	// A `NaN` budget (e.g. `process.stdout.columns - n` when stdout is not a TTY)
+	// means the target width is unknown — return the text untruncated rather than
+	// appending a truncation character to the full string.
+	if (Number.isNaN(columns)) {
+		return text;
+	}
+
 	if (columns < 1) {
 		return '';
 	}
diff --git a/test.js b/test.js
index 90bf745..1ec0ede 100644
--- a/test.js
+++ b/test.js
@@ -23,6 +23,11 @@ test('main', t => {
 	t.is(cliTruncate('u', 1), 'u');
 });
 
+test('NaN columns', t => {
+	t.is(cliTruncate('unicorns', Number.NaN), 'unicorns');
+	t.is(cliTruncate('\u001B[31municorns\u001B[39m', Number.NaN), '\u001B[31municorns\u001B[39m');
+});
+
 test('space option', t => {
 	t.is(cliTruncate('unicorns', 5, {position: 'end', space: true}), 'uni …');
 	t.is(cliTruncate('unicorns', 6, {position: 'start', space: true}), '… orns');