diff --git a/src/Php/CompilerBase.php b/src/Php/CompilerBase.php
index 73608a11..733299df 100644
--- a/src/Php/CompilerBase.php
+++ b/src/Php/CompilerBase.php
@@ -1632,6 +1632,13 @@ class CompilerBase extends \PhpAot\Core\Translator
         if ($v->expr === null) {
             if ($this->functionDef->returnType === self::TYPE_VOID and !$this->context->inClosure) {
                 return 'return;';
+            } elseif ($this->context->inClosure && $this->context->closureReturnTypeCheck) {
+                $tmpVar = $this->genTmpVarName();
+                $this->addLocalVar($tmpVar, self::TYPE_VAR);
+                $code = $tmpVar . ' = ' . self::VALUE_NULL . ';' . PHP_EOL;
+                $code .= $this->genClosureReturnCheck($tmpVar);
+                $code .= $this->getIndent() . 'return ' . $tmpVar . ';';
+                return $code;
             } elseif ($this->functionDef->returnTypeCheck && !$this->context->inClosure) {
                 $tmpVar = $this->genTmpVarName();
                 $this->addLocalVar($tmpVar, self::TYPE_VAR);
@@ -1679,7 +1686,13 @@ class CompilerBase extends \PhpAot\Core\Translator
 
         $exprCode = $this->convertExprType($expr, $returnType, $type);
         // Union/nullable return type: always use tmpVar for runtime check
-        if ($this->functionDef->returnTypeCheck && !$this->context->inClosure) {
+        if ($this->context->inClosure && $this->context->closureReturnTypeCheck) {
+            $tmpVar = $this->genTmpVarName();
+            $this->addLocalVar($tmpVar, self::TYPE_VAR);
+            $code = $tmpVar . ' = ' . $exprCode . ';' . PHP_EOL;
+            $code .= $this->genClosureReturnCheck($tmpVar);
+            $this->context->afterStmtLines[] = $this->getIndent() . 'return ' . $tmpVar . ';';
+        } elseif ($this->functionDef->returnTypeCheck && !$this->context->inClosure) {
             $tmpVar = $this->genTmpVarName();
             $this->addLocalVar($tmpVar, self::TYPE_VAR);
             $code = $tmpVar . ' = ' . $exprCode . ';' . PHP_EOL;
@@ -5845,6 +5858,14 @@ class CompilerBase extends \PhpAot\Core\Translator
 
     protected function genReturnCode(): string
     {
+        if ($this->context->inClosure && $this->context->closureReturnTypeCheck) {
+            $tmpVar = $this->genTmpVarName();
+            $this->addLocalVar($tmpVar, self::TYPE_VAR);
+            $code = $tmpVar . ' = ' . self::VALUE_NULL . ';' . PHP_EOL;
+            $code .= $this->genClosureReturnCheck($tmpVar);
+            $code .= $this->getIndent() . 'return ' . $tmpVar . ';';
+            return $code;
+        }
         if ($this->functionDef->returnType === self::TYPE_VOID) {
             return '';
         }
@@ -5903,9 +5924,25 @@ class CompilerBase extends \PhpAot\Core\Translator
             if ($this->isCallExpr($expr->expr)) {
                 $nativeCall = $expr->expr->getAttribute('nativeCall');
                 if ($nativeCall and $this->getFunction($nativeCall)->returnType === self::TYPE_VOID) {
+                    if ($this->context->closureReturnTypeCheck) {
+                        $tmpVar = $this->genTmpVarName();
+                        $this->addLocalVar($tmpVar, self::TYPE_VAR);
+                        return $beforeCode . PHP_EOL . $code . ';' . PHP_EOL
+                            . $tmpVar . ' = ' . self::VALUE_NULL . ';' . PHP_EOL
+                            . $this->genClosureReturnCheck($tmpVar)
+                            . $this->getIndent() . 'return ' . $tmpVar . ';';
+                    }
                     return $beforeCode . PHP_EOL . $code . ';' . PHP_EOL . 'return ' . self::VALUE_NULL . ';';
                 }
             }
+            if ($this->context->closureReturnTypeCheck) {
+                $tmpVar = $this->genTmpVarName();
+                $this->addLocalVar($tmpVar, self::TYPE_VAR);
+                return $beforeCode . PHP_EOL
+                    . $tmpVar . ' = ' . $code . ';' . PHP_EOL
+                    . $this->genClosureReturnCheck($tmpVar)
+                    . $this->getIndent() . 'return ' . $tmpVar . ';';
+            }
             return $beforeCode . PHP_EOL . 'return ' . $code . ';';
         };
 
@@ -5917,7 +5954,11 @@ class CompilerBase extends \PhpAot\Core\Translator
         $cb = function () use ($expr) {
             $fnCode = $this->parseStmts($expr->stmts);
             if (!$this->isReturnStmtInLastLine($expr->stmts)) {
-                $fnCode .= 'return ' . self::VALUE_NULL . ';' . PHP_EOL;
+                if ($this->context->closureReturnTypeCheck) {
+                    $fnCode .= $this->genReturnCode() . PHP_EOL;
+                } else {
+                    $fnCode .= 'return ' . self::VALUE_NULL . ';' . PHP_EOL;
+                }
             }
             return $fnCode;
         };
diff --git a/src/Php/Constants.php b/src/Php/Constants.php
index 5609f319..770a214e 100644
--- a/src/Php/Constants.php
+++ b/src/Php/Constants.php
@@ -11,53 +11,103 @@ namespace PhpAot\Php;
 class Constants
 {
     public const array CPP_RESERVED_NAMES = [
+        'alignas',
+        'alignof',
+        'and',
+        'and_eq',
+        'asm',
         'auto',
+        'bitand',
+        'bitor',
+        'bool',
         'break',
         'case',
         'catch',
+        'char',
+        'char8_t',
+        'char16_t',
+        'char32_t',
         'class',
-        'struct',
+        'compl',
         'const',
+        'consteval',
+        'constexpr',
+        'constinit',
+        'const_cast',
         'continue',
+        'decltype',
         'default',
+        'delete',
         'do',
+        'double',
+        'dynamic_cast',
         'else',
         'elseif',
         'enum',
+        'explicit',
+        'export',
         'extends',
+        'extern',
+        'false',
         'final',
         'finally',
+        'float',
         'for',
+        'friend',
         'function',
         'global',
+        'goto',
         'if',
-        'bool',
+        'inline',
         'int',
-        'short',
         'long',
-        'unsigned',
-        'void',
-        'signed',
-        'double',
-        'float',
-        'false',
-        'for',
-        'if',
-        'int',
+        'mutable',
+        'namespace',
         'new',
+        'noexcept',
+        'not',
+        'not_eq',
+        'nullptr',
         'null',
-        'var',
-        'char',
         'or',
-        'and',
+        'or_eq',
+        'operator',
         'private',
         'protected',
         'public',
+        'register',
+        'reinterpret_cast',
+        'requires',
         'return',
+        'short',
+        'signed',
+        'sizeof',
         'static',
-        'pipe',
+        'static_assert',
+        'static_cast',
+        'struct',
+        'switch',
         'template',
-        'namespace',
+        'this',
+        'thread_local',
+        'throw',
+        'true',
+        'try',
+        'typedef',
+        'typeid',
+        'typename',
+        'union',
+        'unsigned',
+        'using',
+        'var',
+        'virtual',
+        'void',
+        'volatile',
+        'wchar_t',
+        'while',
+        'xor',
+        'xor_eq',
+        'pipe',
         'errno', // Linux error code
         'this_', // phpx keywords
     ];
diff --git a/src/Php/Context/FunctionContext.php b/src/Php/Context/FunctionContext.php
index e344d411..6f3c145b 100644
--- a/src/Php/Context/FunctionContext.php
+++ b/src/Php/Context/FunctionContext.php
@@ -50,6 +50,8 @@ class FunctionContext
     public array $arguments = [];
     public bool $inLoop = false;
     public bool $inClosure = false;
+    public ?array $closureReturnTypeCheck = null;
+    public string $closureReturnTypeStr = '';
 
     /** True if any break N (N > 1) appears in this function. */
     public bool $hasMultiLevelBreak = false;
@@ -92,6 +94,8 @@ class FunctionContext
         $this->scopeLevel = 0;
         $this->inLoop = false;
         $this->inClosure = false;
+        $this->closureReturnTypeCheck = null;
+        $this->closureReturnTypeStr = '';
         $this->inAssignExpr = false;
     }
 
diff --git a/src/Php/Generator/ClosureGenerator.php b/src/Php/Generator/ClosureGenerator.php
index c2654141..9ee09f9a 100644
--- a/src/Php/Generator/ClosureGenerator.php
+++ b/src/Php/Generator/ClosureGenerator.php
@@ -8,7 +8,12 @@
 
 namespace PhpAot\Php\Generator;
 
+use PhpAot\Php\ArgInfo;
 use PhpAot\Php\Context\FunctionContext;
+use PhpParser\Node;
+use PhpParser\Node\IntersectionType;
+use PhpParser\Node\NullableType;
+use PhpParser\Node\UnionType;
 use PhpParser\NodeAbstract;
 
 trait ClosureGenerator
@@ -36,6 +41,13 @@ trait ClosureGenerator
         $this->context = new FunctionContext();
 
         $this->context->inClosure = true;
+        if ($expr->returnType instanceof NullableType || $expr->returnType instanceof UnionType || $expr->returnType instanceof IntersectionType) {
+            $returnTypeInfo = $this->buildTypeCheckFromNode($expr->returnType);
+            if (!empty($returnTypeInfo['check'])) {
+                $this->context->closureReturnTypeCheck = $returnTypeInfo['check'];
+                $this->context->closureReturnTypeStr = $returnTypeInfo['typeStr'];
+            }
+        }
         $this->indentLevel++;
 
         $requiredArgCount = 0;
@@ -71,6 +83,7 @@ trait ClosureGenerator
                 $this->indentLevel--;
                 $code .= $this->getIndent() . '}' . PHP_EOL;
                 $this->addArgument($var, self::TYPE_ARRAY);
+                $code .= $this->genClosureParamTypeCheck($param, $var, $i, true);
                 continue;
             }
             $argExpr = $param->default === null
@@ -78,6 +91,7 @@ trait ClosureGenerator
                 : 'php::getCallArg(' . $i . ', ' . $this->parseParamDefaultValue($param->default) . ')';
             $code .= $this->getIndent() . 'auto ' . $var . ' = ' . $argExpr . ';' . PHP_EOL;
             $this->addArgument($var, self::TYPE_VAR);
+            $code .= $this->genClosureParamTypeCheck($param, $var, $i, false);
         }
 
         foreach ($uses as $i => $useItem) {
@@ -149,4 +163,26 @@ trait ClosureGenerator
 
         return $code;
     }
+
+    private function genClosureParamTypeCheck(Node\Param $param, string $var, int $index, bool $variadic): string
+    {
+        if (!$param->type instanceof NullableType && !$param->type instanceof UnionType && !$param->type instanceof IntersectionType) {
+            return '';
+        }
+
+        $typeInfo = $this->buildTypeCheckFromNode($param->type);
+        if (empty($typeInfo['check'])) {
+            return '';
+        }
+
+        $argInfo = new ArgInfo();
+        $argInfo->name = $var;
+        $argInfo->type = self::TYPE_VAR;
+        $argInfo->variadic = $variadic;
+        $argInfo->typeCheck = $typeInfo['check'];
+        $argInfo->typeStr = $typeInfo['typeStr'];
+        $argInfo->typeNode = $param->type;
+
+        return $this->genClosureParamCheck($argInfo, $index);
+    }
 }
diff --git a/src/Php/Generator/TypeCheckGenerator.php b/src/Php/Generator/TypeCheckGenerator.php
index 242b44c0..990ad37f 100644
--- a/src/Php/Generator/TypeCheckGenerator.php
+++ b/src/Php/Generator/TypeCheckGenerator.php
@@ -265,10 +265,11 @@ trait TypeCheckGenerator
     protected function genUnionParamTypeErrorExpr(ArgInfo $argInfo, string $valueExpr, string $argNoExpr): string
     {
         $fnName = $this->getTypeCheckCallableName();
+        $paramName = $this->unescapeVarName($argInfo->name);
         return 'php::concat({'
             . 'php::Str(' . $this->genCharPtr($fnName . '(): Argument #', true) . '), '
             . 'php::toString(' . $argNoExpr . '), '
-            . 'php::Str(' . $this->genCharPtr(' ($' . $argInfo->name . ') must be of type ', true) . '), '
+            . 'php::Str(' . $this->genCharPtr(' ($' . $paramName . ') must be of type ', true) . '), '
             . 'php::Str(' . $this->genCharPtr($argInfo->typeStr, true) . '), '
             . 'php::Str(", "), '
             . $valueExpr . '.typeStr(), '
@@ -310,4 +311,118 @@ trait TypeCheckGenerator
         return $code;
     }
 
+    protected function genClosureParamCheck(ArgInfo $argInfo, int $argIndex): string
+    {
+        if (empty($argInfo->typeCheck)) {
+            return '';
+        }
+
+        if ($argInfo->variadic) {
+            return $this->genClosureVariadicParamCheck($argInfo, $argIndex);
+        }
+
+        $conditions = [];
+        foreach ($argInfo->typeCheck as $entry) {
+            $cond = $this->genSingleTypeCondition($argInfo->name, $entry);
+            if ($cond !== '') {
+                $conditions[] = $cond;
+            }
+        }
+        if (empty($conditions)) {
+            return '';
+        }
+
+        $orExpr = implode(' || ', $conditions);
+        $msgExpr = $this->genClosureParamTypeErrorExpr($argInfo, $argInfo->name, (string) ($argIndex + 1));
+
+        $code = $this->getIndent() . 'if (UNEXPECTED(!(' . $orExpr . '))) {' . PHP_EOL;
+        $this->indentLevel++;
+        $code .= $this->getIndent() . 'return php::throwException(zend_ce_type_error, (' . $msgExpr . ').toCString());' . PHP_EOL;
+        $this->indentLevel--;
+        $code .= $this->getIndent() . '}' . PHP_EOL;
+
+        return $code;
+    }
+
+    protected function genClosureVariadicParamCheck(ArgInfo $argInfo, int $argIndex): string
+    {
+        $valueVar = $this->genTmpVarName();
+        $iterVar = $this->genTmpVarName();
+        $argNoVar = $this->genTmpVarName();
+
+        $conditions = [];
+        foreach ($argInfo->typeCheck as $entry) {
+            $cond = $this->genSingleTypeCondition($valueVar, $entry);
+            if ($cond !== '') {
+                $conditions[] = $cond;
+            }
+        }
+        if (empty($conditions)) {
+            return '';
+        }
+
+        $orExpr = implode(' || ', $conditions);
+        $msgExpr = $this->genClosureParamTypeErrorExpr($argInfo, $valueVar, $argNoVar);
+
+        $code = $this->getIndent() . 'for (auto ' . $iterVar . ' = ' . $argInfo->name . '.begin(); ' . $iterVar . ' != ' . $argInfo->name . '.end(); ++' . $iterVar . ') {' . PHP_EOL;
+        $this->indentLevel++;
+        $code .= $this->getIndent() . self::TYPE_VAR . ' ' . $valueVar . ' = ' . $iterVar . '.value();' . PHP_EOL;
+        $code .= $this->getIndent() . self::TYPE_INT . ' ' . $argNoVar . ' = ' . ($argIndex + 1) . ' + ' . $iterVar . '.index();' . PHP_EOL;
+        $code .= $this->getIndent() . 'if (UNEXPECTED(!(' . $orExpr . '))) {' . PHP_EOL;
+        $this->indentLevel++;
+        $code .= $this->getIndent() . 'return php::throwException(zend_ce_type_error, (' . $msgExpr . ').toCString());' . PHP_EOL;
+        $this->indentLevel--;
+        $code .= $this->getIndent() . '}' . PHP_EOL;
+        $this->indentLevel--;
+        $code .= $this->getIndent() . '}' . PHP_EOL;
+
+        return $code;
+    }
+
+    protected function genClosureParamTypeErrorExpr(ArgInfo $argInfo, string $valueExpr, string $argNoExpr): string
+    {
+        $paramName = $this->unescapeVarName($argInfo->name);
+        return 'php::concat({'
+            . 'php::Str(' . $this->genCharPtr('{closure}(): Argument #', true) . '), '
+            . 'php::toString(' . $argNoExpr . '), '
+            . 'php::Str(' . $this->genCharPtr(' ($' . $paramName . ') must be of type ', true) . '), '
+            . 'php::Str(' . $this->genCharPtr($argInfo->typeStr, true) . '), '
+            . 'php::Str(", "), '
+            . $valueExpr . '.typeStr(), '
+            . 'php::Str(" given")'
+            . '})';
+    }
+
+    protected function genClosureReturnCheck(string $varName): string
+    {
+        $typeCheck = $this->context->closureReturnTypeCheck;
+        if (empty($typeCheck)) {
+            return '';
+        }
+
+        $conditions = [];
+        foreach ($typeCheck as $entry) {
+            $cond = $this->genSingleTypeCondition($varName, $entry);
+            if ($cond !== '') {
+                $conditions[] = $cond;
+            }
+        }
+        if (empty($conditions)) {
+            return '';
+        }
+
+        $orExpr = implode(' || ', $conditions);
+        $typeStr = $this->context->closureReturnTypeStr;
+        $msgExpr = 'php::concat(php::concat(php::Str(' . $this->genCharPtr('{closure}', true) . ' "(): Return value must be of type " '
+                 . $this->genCharPtr($typeStr, true) . ' ", "), ' . $varName . '.typeStr()), php::Str(" given"))';
+
+        $code = $this->getIndent() . 'if (UNEXPECTED(!(' . $orExpr . '))) {' . PHP_EOL;
+        $this->indentLevel++;
+        $code .= $this->getIndent() . 'return php::throwException(zend_ce_type_error, (' . $msgExpr . ').toCString());' . PHP_EOL;
+        $this->indentLevel--;
+        $code .= $this->getIndent() . '}' . PHP_EOL;
+
+        return $code;
+    }
+
 }
diff --git a/src/Php/Generator/Utils.php b/src/Php/Generator/Utils.php
index 284bcf8f..85fd3fa7 100644
--- a/src/Php/Generator/Utils.php
+++ b/src/Php/Generator/Utils.php
@@ -62,12 +62,12 @@ trait Utils
 
     protected function escapeVarName(string $name): string
     {
-        if (in_array($name, Constants::CPP_RESERVED_NAMES)) {
-            return '_php__var__' . $name;
-        }
         if ($name === 'this') {
             return 'this_';
         }
+        if (in_array($name, Constants::CPP_RESERVED_NAMES, true)) {
+            return '_php__var__' . $name;
+        }
         return $name;
     }