diff --git a/lib/cli/Shell.php b/lib/cli/Shell.php
index 1adee79..7b3f9bb 100755
--- a/lib/cli/Shell.php
+++ b/lib/cli/Shell.php
@@ -27,21 +27,35 @@ class Shell {
 	static public function columns() {
 		static $columns;
 
+		if ( getenv( 'PHP_CLI_TOOLS_TEST_SHELL_COLUMNS_RESET' ) ) {
+			$columns = null;
+		}
 		if ( null === $columns ) {
-			if (self::is_windows() ) {
-				$output = array();
-				exec('mode CON', $output);
-				foreach ($output as $line) {
-					if (preg_match('/Columns:( )*([0-9]+)/', $line, $matches)) {
-						$columns = (int)$matches[2];
-						break;
+			if ( function_exists( 'exec' ) ) {
+				if ( self::is_windows() ) {
+					// Cater for shells such as Cygwin and Git bash where `mode CON` returns an incorrect value for columns.
+					if ( ( $shell = getenv( 'SHELL' ) ) && preg_match( '/(?:bash|zsh)(?:\.exe)?$/', $shell ) && getenv( 'TERM' ) ) {
+						$columns = (int) exec( 'tput cols' );
+					}
+					if ( ! $columns ) {
+						$return_var = -1;
+						$output = array();
+						exec( 'mode CON', $output, $return_var );
+						if ( 0 === $return_var && $output ) {
+							// Look for second line ending in ": <number>" (searching for "Columns:" will fail on non-English locales).
+							if ( preg_match( '/:\s*[0-9]+\n[^:]+:\s*([0-9]+)\n/', implode( "\n", $output ), $matches ) ) {
+								$columns = (int) $matches[1];
+							}
+						}
+					}
+				} else {
+					if ( getenv( 'TERM' ) ) {
+						$columns = (int) exec( '/usr/bin/env tput cols' );
 					}
 				}
-			} else if (!preg_match('/(^|,)(\s*)?exec(\s*)?(,|$)/', ini_get('disable_functions'))) {
-				$columns = (int) exec('/usr/bin/env tput cols');
 			}
 
-			if ( !$columns ) {
+			if ( ! $columns ) {
 				$columns = 80; // default width of cmd window on Windows OS
 			}
 		}
diff --git a/tests/test-shell.php b/tests/test-shell.php
new file mode 100644
index 0000000..702948c
--- /dev/null
+++ b/tests/test-shell.php
@@ -0,0 +1,53 @@
+<?php
+
+use cli\Shell;
+
+/**
+ * Class TestShell
+ */
+class TestShell extends PHPUnit_Framework_TestCase {
+
+    /**
+     * Test getting TERM columns.
+     */
+    function testColumns() {
+		// Save.
+		$env_term = getenv( 'TERM' );
+		$env_columns = getenv( 'COLUMNS' );
+		$env_is_windows = getenv( 'WP_CLI_TEST_IS_WINDOWS' );
+		$env_shell_columns_reset = getenv( 'PHP_CLI_TOOLS_TEST_SHELL_COLUMNS_RESET' );
+
+		putenv( 'PHP_CLI_TOOLS_TEST_SHELL_COLUMNS_RESET=1' );
+
+		// No TERM should result in default 80.
+
+		putenv( 'TERM' );
+
+		putenv( 'WP_CLI_TEST_IS_WINDOWS=0' );
+		$columns = cli\Shell::columns();
+		$this->assertSame( 80, $columns );
+
+		putenv( 'WP_CLI_TEST_IS_WINDOWS=1' );
+		$columns = cli\Shell::columns();
+		$this->assertSame( 80, $columns );
+
+		// TERM and COLUMNS should result in whatever COLUMNS is.
+
+		putenv( 'TERM=vt100' );
+		putenv( 'COLUMNS=100' );
+
+		putenv( 'WP_CLI_TEST_IS_WINDOWS=0' );
+		$columns = cli\Shell::columns();
+		$this->assertSame( 100, $columns );
+
+		putenv( 'WP_CLI_TEST_IS_WINDOWS=1' );
+		$columns = cli\Shell::columns();
+		$this->assertSame( 100, $columns );
+
+		// Restore.
+		putenv( false === $env_term ? 'TERM' : "TERM=$env_term" );
+		putenv( false === $env_columns ? 'COLUMNS' : "COLUMNS=$env_columns" );
+		putenv( false === $env_is_windows ? 'WP_CLI_TEST_IS_WINDOWS' : "WP_CLI_TEST_IS_WINDOWS=$env_is_windows" );
+		putenv( false === $env_shell_columns_reset ? 'PHP_CLI_TOOLS_TEST_SHELL_COLUMNS_RESET' : "PHP_CLI_TOOLS_TEST_SHELL_COLUMNS_RESET=$env_shell_columns_reset" );
+	}
+}