diff --git a/src/Type/TypeCombinator.php b/src/Type/TypeCombinator.php
index af60550c859..df18959ae24 100644
--- a/src/Type/TypeCombinator.php
+++ b/src/Type/TypeCombinator.php
@@ -353,8 +353,9 @@ public static function union(Type ...$types): Type
 					[$a, $b] = $compareResult;
 					if ($a !== null) {
 						$types[$i] = $a;
-						array_splice($scalarTypeItems, $j--, 1);
+						array_splice($scalarTypeItems, $j, 1);
 						$scalarTypeItemsCount--;
+						$j = -1;
 						continue 1;
 					}
 					if ($b !== null) {
diff --git a/tests/PHPStan/Analyser/nsrt/bug-14610.php b/tests/PHPStan/Analyser/nsrt/bug-14610.php
new file mode 100644
index 00000000000..3ad65a6e069
--- /dev/null
+++ b/tests/PHPStan/Analyser/nsrt/bug-14610.php
@@ -0,0 +1,68 @@
+<?php
+
+namespace Bug14610;
+
+use function PHPStan\Testing\assertType;
+
+function test(): void
+{
+	$value = 0;
+
+	if (isset($_SESSION['test'])) {
+		$value = rand(0,3);
+		if ($value == 1) {
+		}
+	}
+
+	assertType('int<0, 3>', $value);
+
+	if ($value == 0) {
+		assertType('array<mixed>', $_SESSION);
+		$result = isset($_SESSION['test']); // should not be reported as always exists
+	}
+}
+
+function testWithOtherSuperglobals(): void
+{
+	$value = 0;
+
+	if (isset($_GET['key'])) {
+		$value = rand(0,3);
+		if ($value == 1) {
+		}
+	}
+
+	if ($value == 0) {
+		$result = isset($_GET['key']);
+	}
+}
+
+function testWithStrictComparison(): void
+{
+	$value = 0;
+
+	if (isset($_SESSION['test'])) {
+		$value = rand(0,3);
+		if ($value === 1) {
+		}
+	}
+
+	if ($value === 0) {
+		$result = isset($_SESSION['test']);
+	}
+}
+
+function testWithDifferentKey(): void
+{
+	$value = 0;
+
+	if (isset($_SESSION['test'])) {
+		$value = rand(0,3);
+		if ($value == 1) {
+		}
+	}
+
+	if ($value == 0) {
+		$result = isset($_SESSION['other']);
+	}
+}
diff --git a/tests/PHPStan/Rules/Variables/IssetRuleTest.php b/tests/PHPStan/Rules/Variables/IssetRuleTest.php
index c1492e62901..ff2cf199417 100644
--- a/tests/PHPStan/Rules/Variables/IssetRuleTest.php
+++ b/tests/PHPStan/Rules/Variables/IssetRuleTest.php
@@ -574,4 +574,11 @@ public function testBug14393(): void
 		]);
 	}
 
+	public function testBug14610(): void
+	{
+		$this->treatPhpDocTypesAsCertain = true;
+
+		$this->analyse([__DIR__ . '/../../Analyser/nsrt/bug-14610.php'], []);
+	}
+
 }
diff --git a/tests/PHPStan/Type/TypeCombinatorTest.php b/tests/PHPStan/Type/TypeCombinatorTest.php
index 55f79c743cc..f325c638da4 100644
--- a/tests/PHPStan/Type/TypeCombinatorTest.php
+++ b/tests/PHPStan/Type/TypeCombinatorTest.php
@@ -1642,6 +1642,42 @@ public static function dataUnion(): iterable
 				IntegerType::class,
 				'int',
 			],
+			[
+				[
+					new UnionType([
+						new ConstantIntegerType(0),
+						IntegerRangeType::fromInterval(2, 3),
+					]),
+					new ConstantIntegerType(1),
+				],
+				IntegerRangeType::class,
+				'int<0, 3>',
+			],
+			[
+				[
+					new ConstantIntegerType(1),
+					new UnionType([
+						new ConstantIntegerType(0),
+						IntegerRangeType::fromInterval(2, 3),
+					]),
+				],
+				IntegerRangeType::class,
+				'int<0, 3>',
+			],
+			[
+				[
+					new UnionType([
+						new ConstantIntegerType(0),
+						IntegerRangeType::fromInterval(2, 3),
+					]),
+					new UnionType([
+						new ConstantIntegerType(10),
+						new ConstantIntegerType(1),
+					]),
+				],
+				UnionType::class,
+				'10|int<0, 3>',
+			],
 			[
 				[
 					new MixedType(),