diff --git a/src/Type/TypeCombinator.php b/src/Type/TypeCombinator.php
index 19291fdae29..802a0e3df97 100644
--- a/src/Type/TypeCombinator.php
+++ b/src/Type/TypeCombinator.php
@@ -171,7 +171,8 @@ public static function union(Type ...$types): Type
 			}
 			if ($types[$i] instanceof ConstantScalarType) {
 				$type = $types[$i];
-				$scalarTypes[get_class($type)][md5($type->describe(VerbosityLevel::cache()))] = $type;
+				$key = $type instanceof ConstantIntegerType ? $type->getValue() : md5($type->describe(VerbosityLevel::cache()));
+				$scalarTypes[get_class($type)][$key] = $type;
 				unset($types[$i]);
 				continue;
 			}
@@ -256,6 +257,33 @@ public static function union(Type ...$types): Type
 				$types[] = new BooleanType();
 				continue;
 			}
+			if ($classType === ConstantIntegerType::class) {
+				/** @var int[] */
+				$integers = array_keys($scalarTypeItems);
+				sort($integers);
+				/** @var ConstantIntegerType[] */
+				$loneIntegers = [];
+				$rangeStart = null;
+				$rangeEnd = null;
+				for ($i = 0; $i < count($integers); $i++) {
+					if ($i < count($integers) - 1 && $integers[$i] + 1 === $integers[$i + 1]) {
+						$rangeStart ??= $integers[$i];
+						$rangeEnd = $integers[$i + 1];
+					} elseif ($rangeStart === null) {
+						$loneIntegers[] = $scalarTypeItems[$integers[$i]];
+					} else {
+						$types[] = IntegerRangeType::fromInterval($rangeStart, $rangeEnd);
+						$rangeStart = null;
+						$rangeEnd = null;
+					}
+				}
+				if (count($loneIntegers) > self::CONSTANT_SCALAR_UNION_THRESHOLD) {
+					$types[] = new IntegerType();
+				} else {
+					array_push($types, ...$loneIntegers);
+				}
+				continue;
+			}
 			foreach ($scalarTypeItems as $type) {
 				if (count($scalarTypeItems) > self::CONSTANT_SCALAR_UNION_THRESHOLD) {
 					$types[] = $type->generalize();
diff --git a/tests/PHPStan/Rules/Classes/InstantiationRuleTest.php b/tests/PHPStan/Rules/Classes/InstantiationRuleTest.php
index 62bf98915ba..b99531a8ea9 100644
--- a/tests/PHPStan/Rules/Classes/InstantiationRuleTest.php
+++ b/tests/PHPStan/Rules/Classes/InstantiationRuleTest.php
@@ -193,6 +193,10 @@ public function testInstantiation(): void
 					'Class TestInstantiation\ClassExtendingAbstractConstructor constructor invoked with 0 parameters, 1 required.',
 					273,
 				],
+				[
+					'Parameter #2 $y of class TestInstantiation\IntRange constructor expects int<1,7>, int<1, 8> given.',
+					291,
+				],
 			]
 		);
 	}
diff --git a/tests/PHPStan/Rules/Classes/data/instantiation.php b/tests/PHPStan/Rules/Classes/data/instantiation.php
index 58c5b2cf60c..ae3aef80f08 100644
--- a/tests/PHPStan/Rules/Classes/data/instantiation.php
+++ b/tests/PHPStan/Rules/Classes/data/instantiation.php
@@ -274,3 +274,29 @@ public function doBar()
 	}
 
 }
+
+final class IntRange
+{
+    /**
+     * @psalm-var 1|2|3|4|5|6|7|8
+     */
+    private int $x;
+
+    public static function fromInt(int $x): self
+    {
+        if ($x < 1 || $x > 8) {
+            throw new InvalidArgumentException;
+        }
+
+        return new self($x, $x);
+    }
+
+    /**
+     * @psalm-param 1|2|3|4|5|6|7|8 $x
+     * @psalm-param 1|2|3|4|5|6|7 $y
+     */
+    private function __construct(int $x, int $y)
+    {
+        $y = $this->x = $x;
+    }
+}
diff --git a/tests/PHPStan/Rules/Functions/ReturnTypeRuleTest.php b/tests/PHPStan/Rules/Functions/ReturnTypeRuleTest.php
index 3781881114b..3e454fe1934 100644
--- a/tests/PHPStan/Rules/Functions/ReturnTypeRuleTest.php
+++ b/tests/PHPStan/Rules/Functions/ReturnTypeRuleTest.php
@@ -61,6 +61,10 @@ public function testReturnTypeRule(): void
 				'Function ReturnTypes\returnNever() should never return but return statement found.',
 				181,
 			],
+			[
+				'Function ReturnTypes\returnRangeBad() should return int<1, 7> but returns int<1, 8>.',
+				203,
+			],
 		]);
 	}
 
diff --git a/tests/PHPStan/Rules/Functions/data/returnTypes.php b/tests/PHPStan/Rules/Functions/data/returnTypes.php
index 3e15651c697..49355cc5a2d 100644
--- a/tests/PHPStan/Rules/Functions/data/returnTypes.php
+++ b/tests/PHPStan/Rules/Functions/data/returnTypes.php
@@ -180,3 +180,25 @@ function returnNever()
 {
 	return;
 }
+
+/**
+ * @return 1|2|3|4|5|6|7|8
+ */
+function returnRange(int $x) : int {
+	if ($x < 1 || $x > 8) {
+		throw new InvalidArgumentException;
+	}
+
+	return $x;
+}
+
+/**
+ * @return 1|2|3|4|5|6|7
+ */
+function returnRangeBad(int $x) : int {
+	if ($x < 1 || $x > 8) {
+		throw new InvalidArgumentException;
+	}
+
+	return $x;
+}
diff --git a/tests/PHPStan/Type/TypeCombinatorTest.php b/tests/PHPStan/Type/TypeCombinatorTest.php
index a42c4e26009..5d132c7e2c6 100644
--- a/tests/PHPStan/Type/TypeCombinatorTest.php
+++ b/tests/PHPStan/Type/TypeCombinatorTest.php
@@ -1760,6 +1760,33 @@ public function dataUnion(): array
 				MixedType::class,
 				'mixed=implicit',
 			],
+			[
+				[
+					new ConstantIntegerType(1),
+					new ConstantIntegerType(2),
+					new ConstantIntegerType(3),
+					new ConstantIntegerType(4),
+					new ConstantIntegerType(5),
+					new ConstantIntegerType(6),
+				],
+				IntegerRangeType::class,
+				'int<1,6>',
+			],
+			[
+				[
+					new ConstantIntegerType(1),
+					new ConstantIntegerType(2),
+					new ConstantIntegerType(3),
+					new ConstantIntegerType(5),
+					new ConstantIntegerType(7),
+					new ConstantIntegerType(8),
+					new ConstantIntegerType(9),
+					new ConstantIntegerType(10),
+					new ConstantIntegerType(11),
+				],
+				UnionType::class,
+				'int<1,5>|7|int<8,11>',
+			],
 		];
 	}