diff --git a/phpunit/code/php-int-max-fold-global.php b/phpunit/code/php-int-max-fold-global.php
new file mode 100644
index 00000000..5c4f8a27
--- /dev/null
+++ b/phpunit/code/php-int-max-fold-global.php
@@ -0,0 +1,11 @@
+<?php
+
+function lowercaseIsRuntime()
+{
+    return php_int_max + 1;
+}
+
+function uppercaseFolds(): float
+{
+    return PHP_INT_MAX + 1;
+}
diff --git a/phpunit/code/php-int-max-fold-namespace.php b/phpunit/code/php-int-max-fold-namespace.php
new file mode 100644
index 00000000..5abe3d15
--- /dev/null
+++ b/phpunit/code/php-int-max-fold-namespace.php
@@ -0,0 +1,15 @@
+<?php
+
+namespace FoldNs;
+
+const PHP_INT_MAX = 5;
+
+function shadowedFold(): int
+{
+    return PHP_INT_MAX + 1;
+}
+
+function globalFold(): float
+{
+    return \PHP_INT_MAX + 1;
+}
diff --git a/phpunit/src/PhpIntMaxFoldTest.php b/phpunit/src/PhpIntMaxFoldTest.php
new file mode 100644
index 00000000..3229c4b1
--- /dev/null
+++ b/phpunit/src/PhpIntMaxFoldTest.php
@@ -0,0 +1,50 @@
+<?php
+
+use TypePhp\CompilerTest;
+
+/**
+ * The PHP_INT_MAX/PHP_INT_MIN constant folder must resolve the constant name
+ * like PHP does: case-sensitively, and only to the real global constant. An
+ * unqualified fetch inside a namespace resolves to Namespace\PHP_INT_MAX
+ * first, and a lowercase php_int_max is an undefined constant, not the
+ * global value.
+ */
+final class PhpIntMaxFoldTest extends \BaseTest
+{
+    public function testNamespacedConstantShadowsGlobalAndIsNotFolded(): void
+    {
+        $code = $this->compileFixture('php-int-max-fold-namespace.php');
+
+        // The unqualified fetch reads the namespaced constant at runtime.
+        self::assertStringContainsString('_const_var_FoldNs__PHP_INT_MAX', $code);
+        // The fully qualified fetch still folds to the overflowed float.
+        self::assertStringContainsString('9.2233720368547758e+18', $code);
+    }
+
+    public function testLowercaseNameIsARuntimeConstantLookup(): void
+    {
+        $code = $this->compileFixture('php-int-max-fold-global.php');
+
+        // php_int_max is undefined in PHP; it must stay a runtime lookup
+        // that raises the undefined-constant Error, never fold.
+        self::assertStringContainsString('php::constant(', $code);
+        // The exact-case global fetch keeps folding.
+        self::assertStringContainsString('9.2233720368547758e+18', $code);
+    }
+
+    private function compileFixture(string $file): string
+    {
+        global $translator;
+
+        $compiler = CompilerTest::create(TYPEPHP_ROOT_PATH);
+        $translator = $compiler;
+        $source = TYPEPHP_ROOT_PATH . '/phpunit/code/' . $file;
+        $compiler->addFiles([$source]);
+        $compiler->prepareFile($source);
+        $generated = $compiler->convertFile($source);
+        $code = file_get_contents($generated);
+
+        self::assertIsString($code);
+        return $code;
+    }
+}
diff --git a/src/Parser/BinaryOpTrait.php b/src/Parser/BinaryOpTrait.php
index 8ba4e9aa..e2c35d76 100644
--- a/src/Parser/BinaryOpTrait.php
+++ b/src/Parser/BinaryOpTrait.php
@@ -393,10 +393,13 @@ protected function constantNumericValue(NodeAbstract $expr, bool $nativeSemantic
             return $value === null ? null : -$value;
         }
         if ($expr instanceof Node\Expr\ConstFetch) {
-            $name = strtolower($expr->name->toString());
+            // PHP constants are case-sensitive and unqualified names resolve
+            // through the namespace first, so only a fetch that provably
+            // names the global constant may fold to its value.
+            $name = $this->resolveGlobalFoldableConstantName($expr);
             return match ($name) {
-                'php_int_max' => PHP_INT_MAX,
-                'php_int_min' => PHP_INT_MIN,
+                'PHP_INT_MAX' => PHP_INT_MAX,
+                'PHP_INT_MIN' => PHP_INT_MIN,
                 default => null,
             };
         }
@@ -441,6 +444,34 @@ protected function constantNumericValue(NodeAbstract $expr, bool $nativeSemantic
         };
     }
 
+    /**
+     * Resolve a constant fetch to the global constant name it provably
+     * denotes, or null when the fetch may refer to something else.
+     *
+     * A `use const` alias resolves to its target. A fully qualified name is
+     * already global. An unqualified name inside a namespace participates in
+     * PHP's runtime fallback (Namespace\NAME can be defined before the fetch
+     * executes), so it never provably names the global constant. A qualified
+     * relative name resolves inside a namespace/import and is never global.
+     */
+    protected function resolveGlobalFoldableConstantName(Node\Expr\ConstFetch $expr): ?string
+    {
+        $name = ltrim($expr->name->toString(), '\\');
+        if (isset($this->useConstants[$name])) {
+            return ltrim($this->useConstants[$name], '\\');
+        }
+        if ($expr->name instanceof Node\Name\FullyQualified) {
+            return $name;
+        }
+        if (!$expr->name->isUnqualified()) {
+            return null;
+        }
+        if ($this->namespace) {
+            return null;
+        }
+        return $name;
+    }
+
     protected function constantDivisionValue(int|float $left, int|float $right, bool $nativeSemantics): int|float|null
     {
         if ($right == 0) {
diff --git a/tests/compiler/const/php-int-max-namespace-shadow.phpt b/tests/compiler/const/php-int-max-namespace-shadow.phpt
new file mode 100644
index 00000000..d25063de
--- /dev/null
+++ b/tests/compiler/const/php-int-max-namespace-shadow.phpt
@@ -0,0 +1,32 @@
+--TEST--
+Namespaced PHP_INT_MAX shadows the global constant in unqualified fetches
+--FILE--
+<?php
+
+namespace N {
+    const PHP_INT_MAX = 5;
+
+    function shadowed(): int
+    {
+        return PHP_INT_MAX + 1;
+    }
+
+    function globalValue(): float
+    {
+        return \PHP_INT_MAX + 1;
+    }
+}
+
+namespace {
+    function main(): void
+    {
+        var_dump(\N\shadowed());
+        var_dump(\N\globalValue());
+        var_dump(PHP_INT_MAX + 1);
+    }
+}
+?>
+--EXPECT--
+int(6)
+float(9.223372036854776E+18)
+float(9.223372036854776E+18)