diff --git a/lib/cli/Shell.php b/lib/cli/Shell.php
index b9ae380..9afb257 100755
--- a/lib/cli/Shell.php
+++ b/lib/cli/Shell.php
@@ -31,7 +31,7 @@ static public function columns() {
 			$columns = null;
 		}
 		if ( null === $columns ) {
-			if ( function_exists( 'exec' ) ) {
+			if ( ! ( $columns = (int) getenv( 'COLUMNS' ) ) && 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' ) ) {
@@ -49,15 +49,13 @@ static public function columns() {
 						}
 					}
 				} else {
-					if ( ! ( $columns = (int) getenv( 'COLUMNS' ) ) ) {
-						$size = exec( '/usr/bin/env stty size 2>/dev/null' );
-						if ( '' !== $size && preg_match( '/[0-9]+ ([0-9]+)/', $size, $matches ) ) {
-							$columns = (int) $matches[1];
-						}
-						if ( ! $columns ) {
-							if ( getenv( 'TERM' ) ) {
-								$columns = (int) exec( '/usr/bin/env tput cols 2>/dev/null' );
-							}
+					$size = exec( '/usr/bin/env stty size 2>/dev/null' );
+					if ( '' !== $size && preg_match( '/[0-9]+ ([0-9]+)/', $size, $matches ) ) {
+						$columns = (int) $matches[1];
+					}
+					if ( ! $columns ) {
+						if ( getenv( 'TERM' ) ) {
+							$columns = (int) exec( '/usr/bin/env tput cols 2>/dev/null' );
 						}
 					}
 				}
@@ -114,7 +112,7 @@ static public function hide($hidden = true) {
 	 */
 	static public function is_windows() {
 		$test_is_windows = getenv( 'WP_CLI_TEST_IS_WINDOWS' );
-		if ( false !== $test_is_windows ) {
+		if ( false !== $test_is_windows && '' !== $test_is_windows ) {
 			return (bool) $test_is_windows;
 		}
 		return strtoupper( substr( PHP_OS, 0, 3 ) ) === 'WIN';
diff --git a/tests/Test_Shell.php b/tests/Test_Shell.php
index d2bc71e..f793027 100644
--- a/tests/Test_Shell.php
+++ b/tests/Test_Shell.php
@@ -49,7 +49,15 @@ function testColumns() {
 		// 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" );
+		if ( false === $env_is_windows ) {
+			if ( strtoupper( substr( PHP_OS, 0, 3 ) ) === 'WIN' ) {
+				putenv( 'WP_CLI_TEST_IS_WINDOWS=' );
+			} else {
+				putenv( 'WP_CLI_TEST_IS_WINDOWS' );
+			}
+		} else {
+			putenv( "WP_CLI_TEST_IS_WINDOWS=$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" );
 	}
 }
diff --git a/tests/Test_Table.php b/tests/Test_Table.php
index ca03f71..eb6a2eb 100644
--- a/tests/Test_Table.php
+++ b/tests/Test_Table.php
@@ -3,6 +3,7 @@
 use cli\Colors;
 use cli\Table;
 use cli\Table\Ascii;
+use cli\Shell;
 use WP_CLI\Tests\TestCase;
 
 /**
@@ -85,7 +86,7 @@ public function test_column_odd_single_width_with_double_width() {
 
 		$strip_borders = function ( $a ) {
 			return array_map( function ( $v ) {
-				return substr( $v, 2, -2 );
+				return substr( rtrim( $v, "\r" ), 2, -2 );
 			}, $a );
 		};
 
@@ -96,7 +97,7 @@ public function test_column_odd_single_width_with_double_width() {
 		$result = $strip_borders( explode( "\n", $out ) );
 
 		$this->assertSame( 3, count( $result ) );
-		$this->assertSame( '1あいうえ ', $result[0] ); // 1 single width, 4 double-width, space = 10.
+		$this->assertSame( '1あいうえ ', $result[0] ); // 1 single-width, 4 double-width, space = 10.
 		$this->assertSame( 'おか2きくｶ', $result[1] ); // 2 double-width, 1 single-width, 2 double-width, 1 half-width = 10.
 		$this->assertSame( 'けこ      ', $result[2] ); // 2 double-width, 8 spaces = 10.
 
diff --git a/tests/Test_Table_Ascii.php b/tests/Test_Table_Ascii.php
index 3e683b8..39cc99f 100644
--- a/tests/Test_Table_Ascii.php
+++ b/tests/Test_Table_Ascii.php
@@ -386,6 +386,9 @@ private function assertInOutEquals(array $input, $output) {
 	 * @param mixed $expected Expected output
 	 */
 	private function assertOutFileEqualsWith($expected) {
-		$this->assertEquals($expected, file_get_contents($this->_mockFile));
+		$actual = file_get_contents($this->_mockFile);
+		$actual = str_replace("\r\n", "\n", $actual);
+		$expected = str_replace("\r\n", "\n", $expected);
+		$this->assertEquals($expected, $actual);
 	}
 }