diff --git a/composer.json b/composer.json
index 7d8ae3bdf..d9e1125ed 100644
--- a/composer.json
+++ b/composer.json
@@ -29,7 +29,7 @@
 		"nette/utils": "to use filter |webalize"
 	},
 	"conflict": {
-		"nette/application": "<2.4.1"
+		"nette/application": "<3.0"
 	},
 	"autoload": {
 		"classmap": ["src/"]
@@ -37,7 +37,7 @@
 	"minimum-stability": "dev",
 	"extra": {
 		"branch-alias": {
-			"dev-master": "2.5-dev"
+			"dev-master": "3.0-dev"
 		}
 	}
 }
diff --git a/src/Latte/Engine.php b/src/Latte/Engine.php
index eaef49454..37e652ae3 100644
--- a/src/Latte/Engine.php
+++ b/src/Latte/Engine.php
@@ -17,7 +17,7 @@ class Engine
 {
 	use Strict;
 
-	public const VERSION = '2.5.2';
+	public const VERSION = '3.0-dev';
 
 	/** Content types */
 	public const
diff --git a/src/Latte/Macros/BlockMacros.php b/src/Latte/Macros/BlockMacros.php
index 25e9d12db..e7c30641f 100644
--- a/src/Latte/Macros/BlockMacros.php
+++ b/src/Latte/Macros/BlockMacros.php
@@ -268,6 +268,9 @@ public function macroBlock(MacroNode $node, PhpWriter $writer)
 				return "\$this->checkBlockContentType($blockType, $fname);"
 					. "\$this->blockQueue[$fname][] = [\$this, '{$node->data->func}'];";
 			}
+
+		} elseif ($name[0] === '_') {
+			throw new CompileException("Block name '$name' must not start with an underscore.");
 		}
 
 		// static snippet/snippetArea
diff --git a/src/Latte/Runtime/Filters.php b/src/Latte/Runtime/Filters.php
index cdf184ef3..81e06afe1 100644
--- a/src/Latte/Runtime/Filters.php
+++ b/src/Latte/Runtime/Filters.php
@@ -316,7 +316,7 @@ public static function strip(FilterInfo $info, string $s): string
 	 * @param  bool  $strip  stripping mode
 	 * @return string HTML
 	 */
-	public static function spacelessHtml(string $s, int $phase = null, bool &$strip = true): string
+	public static function spacelessHtml(string $s, ?int $phase = null, bool &$strip = true): string
 	{
 		if ($phase & PHP_OUTPUT_HANDLER_START) {
 			$s = ltrim($s);
@@ -324,18 +324,25 @@ public static function spacelessHtml(string $s, int $phase = null, bool &$strip
 		if ($phase & PHP_OUTPUT_HANDLER_FINAL) {
 			$s = rtrim($s);
 		}
-		return preg_replace_callback(
+		$return = (string) preg_replace_callback( // Other cases
 			'#[ \t\r\n]+|<(/)?(textarea|pre|script)(?=\W)#si',
-			function ($m) use (&$strip) {
+			static function (array $m) use (&$strip): string {
 				if (empty($m[2])) {
-					return $strip ? ' ' : $m[0];
-				} else {
-					$strip = !empty($m[1]);
-					return $m[0];
+					return (string) $strip ? ' ' : $m[0];
 				}
+				$strip = !empty($m[1]);
+				return (string) $m[0];
 			},
 			$s
 		);
+		$return = (string) preg_replace_callback( // <script> for include JS file
+			'/<script\s*([^>]+?)>(?:\s*)<\/script>/',
+			static function (array $m) use (&$strip): string {
+				return $strip ? '<script ' . trim(preg_replace('/\s+/', ' ', $m[1])) . '></script>' : (string) $m[0];
+			},
+			$return
+		);
+		return $return;
 	}
 
 
diff --git a/src/Latte/Runtime/ISnippetBridge.php b/src/Latte/Runtime/ISnippetBridge.php
index 5829e758f..9c9f3358b 100644
--- a/src/Latte/Runtime/ISnippetBridge.php
+++ b/src/Latte/Runtime/ISnippetBridge.php
@@ -16,17 +16,17 @@
  */
 interface ISnippetBridge
 {
-	function isSnippetMode();
+	function isSnippetMode(): bool;
 
-	function setSnippetMode($snippetMode);
+	function setSnippetMode(bool $snippetMode);
 
-	function needsRedraw($name);
+	function needsRedraw(string $name): bool;
 
-	function markRedrawn($name);
+	function markRedrawn(string $name): void;
 
-	function getHtmlId($name);
+	function getHtmlId(string $name): string;
 
-	function addSnippet($name, $content);
+	function addSnippet(string $name, string $content): void;
 
-	function renderChildren();
+	function renderChildren(): void;
 }
diff --git a/tests/Latte/BlockMacros.block5.phpt b/tests/Latte/BlockMacros.block5.phpt
index 9c7311199..9bbc185d6 100644
--- a/tests/Latte/BlockMacros.block5.phpt
+++ b/tests/Latte/BlockMacros.block5.phpt
@@ -26,3 +26,7 @@ Assert::match(
 	'<br class="123">',
 	$latte->renderToString('{block test}<br n:class="$var">{/block}', ['var' => 123])
 );
+
+Assert::exception(function () use ($latte) {
+	$latte->renderToString('{define _foobar}Hello{/define}');
+}, Latte\CompileException::class, "Block name '_foobar' must not start with an underscore.");
diff --git a/tests/Latte/mocks/SnippetBridge.php b/tests/Latte/mocks/SnippetBridge.php
index 1fced3731..7bf3fcb63 100644
--- a/tests/Latte/mocks/SnippetBridge.php
+++ b/tests/Latte/mocks/SnippetBridge.php
@@ -18,19 +18,19 @@ public function isSnippetMode(): bool
 	}
 
 
-	public function setSnippetMode($snippetMode)
+	public function setSnippetMode(bool $snippetMode)
 	{
 		$this->snippetMode = $snippetMode;
 	}
 
 
-	public function needsRedraw($name): bool
+	public function needsRedraw(string $name): bool
 	{
 		return $this->invalid === true || isset($this->invalid[$name]);
 	}
 
 
-	public function markRedrawn($name): void
+	public function markRedrawn(string $name): void
 	{
 		if ($this->invalid !== true) {
 			unset($this->invalid[$name]);
@@ -38,13 +38,13 @@ public function markRedrawn($name): void
 	}
 
 
-	public function getHtmlId($name): string
+	public function getHtmlId(string $name): string
 	{
 		return $name;
 	}
 
 
-	public function addSnippet($name, $content): void
+	public function addSnippet(string $name, string $content): void
 	{
 		$this->payload[$name] = $content;
 	}