diff --git a/src/Runtime.php b/src/Runtime.php
index f143ae9..736dd71 100644
--- a/src/Runtime.php
+++ b/src/Runtime.php
@@ -37,14 +37,19 @@ public static function lo(array $v): string
     /**
      * For {{#if}} and {{#unless}}.
      *
-     * @param array<array<mixed>|string|int>|string|int|float|bool|null $v value to be tested
+     * @param array<array<mixed>|string|int>|string|\Stringable|int|float|bool|null $v value to be tested
      * @param bool $zero include zero as true
      *
      * @return bool Return true when the value is not null nor false.
      */
-    public static function ifvar(mixed $v, bool $zero): bool
+    public static function ifvar(mixed $v, bool $zero = false): bool
     {
-        return $v !== null && $v !== false && ($zero || ($v !== 0 && $v !== 0.0)) && $v !== '' && (!is_array($v) || count($v) > 0);
+        return $v !== null
+            && $v !== false
+            && ($zero || ($v !== 0 && $v !== 0.0))
+            && $v !== ''
+            && (!$v instanceof \Stringable || (string) $v !== '')
+            && (!is_array($v) || count($v) > 0);
     }
 
     /**
diff --git a/tests/RuntimeTest.php b/tests/RuntimeTest.php
index 109857f..c696624 100644
--- a/tests/RuntimeTest.php
+++ b/tests/RuntimeTest.php
@@ -10,17 +10,19 @@ class RuntimeTest extends TestCase
 {
     public function testIfVar(): void
     {
-        $this->assertFalse(Runtime::ifvar(null, false));
-        $this->assertFalse(Runtime::ifvar(0, false));
+        $this->assertFalse(Runtime::ifvar(null));
+        $this->assertFalse(Runtime::ifvar(0));
         $this->assertTrue(Runtime::ifvar(0, true));
-        $this->assertFalse(Runtime::ifvar(false, false));
-        $this->assertTrue(Runtime::ifvar(true, false));
-        $this->assertTrue(Runtime::ifvar(1, false));
-        $this->assertFalse(Runtime::ifvar('', false));
-        $this->assertTrue(Runtime::ifvar('0', false));
-        $this->assertFalse(Runtime::ifvar([], false));
-        $this->assertTrue(Runtime::ifvar([''], false));
-        $this->assertTrue(Runtime::ifvar([0], false));
+        $this->assertFalse(Runtime::ifvar(false));
+        $this->assertTrue(Runtime::ifvar(true));
+        $this->assertTrue(Runtime::ifvar(1));
+        $this->assertFalse(Runtime::ifvar(''));
+        $this->assertTrue(Runtime::ifvar('0'));
+        $this->assertFalse(Runtime::ifvar([]));
+        $this->assertTrue(Runtime::ifvar(['']));
+        $this->assertTrue(Runtime::ifvar([0]));
+        $this->assertFalse(Runtime::ifvar(self::createStringable('')));
+        $this->assertTrue(Runtime::ifvar(self::createStringable('0')));
     }
 
     public function testIsec(): void
@@ -41,4 +43,16 @@ public function testWi(): void
         $this->assertSame('{"a":"b"}', Runtime::wi($cx, ['a' => 'b'], null, ['a' => 'c'], function ($c, $i) {return json_encode($i); }));
         $this->assertSame('-b=', Runtime::wi($cx, 'b', null, ['a' => 'b'], function ($c, $i) {return "-$i="; }));
     }
+
+    private static function createStringable(string $value): \Stringable
+    {
+        return new class ($value) implements \Stringable {
+            public function __construct(private string $value) {}
+
+            public function __toString(): string
+            {
+                return $this->value;
+            }
+        };
+    }
 }