diff --git a/src/Analyser/MutatingScope.php b/src/Analyser/MutatingScope.php
index 136e2023ba2..57cee2455cf 100644
--- a/src/Analyser/MutatingScope.php
+++ b/src/Analyser/MutatingScope.php
@@ -3274,7 +3274,11 @@ public function filterBySpecifiedTypes(SpecifiedTypes $specifiedTypes): self
 	public function addConditionalExpressions(string $exprString, array $conditionalExpressionHolders): self
 	{
 		$conditionalExpressions = $this->conditionalExpressions;
-		$conditionalExpressions[$exprString] = $conditionalExpressionHolders;
+		if (isset($conditionalExpressions[$exprString])) {
+			$conditionalExpressions[$exprString] = array_merge($conditionalExpressions[$exprString], $conditionalExpressionHolders);
+		} else {
+			$conditionalExpressions[$exprString] = $conditionalExpressionHolders;
+		}
 		return $this->scopeFactory->create(
 			$this->context,
 			$this->isDeclareStrictTypes(),
@@ -3295,6 +3299,14 @@ public function addConditionalExpressions(string $exprString, array $conditional
 		);
 	}
 
+	/**
+	 * @return array<string, ConditionalExpressionHolder[]>
+	 */
+	public function getConditionalExpressions(): array
+	{
+		return $this->conditionalExpressions;
+	}
+
 	public function exitFirstLevelStatements(): self
 	{
 		if (!$this->inFirstLevelStatement) {
diff --git a/src/Analyser/TypeSpecifier.php b/src/Analyser/TypeSpecifier.php
index 4f3e7f9c433..7be4501d1ad 100644
--- a/src/Analyser/TypeSpecifier.php
+++ b/src/Analyser/TypeSpecifier.php
@@ -756,7 +756,9 @@ public function specifyTypesInCondition(
 				) {
 					$types = $leftTypes->normalize($scope);
 				} else {
-					$types = $leftTypes->normalize($scope)->intersectWith($rightTypes->normalize($rightScope));
+					$leftNormalized = $this->resolveConditionalExpressions($scope, $leftTypes->normalize($scope));
+					$rightNormalized = $this->resolveConditionalExpressions($rightScope, $rightTypes->normalize($rightScope));
+					$types = $leftNormalized->intersectWith($rightNormalized);
 				}
 			} else {
 				$types = $leftTypes->unionWith($rightTypes);
@@ -2098,6 +2100,59 @@ private function processBooleanNotSureConditionalTypes(Scope $scope, SpecifiedTy
 		return [];
 	}
 
+	private function resolveConditionalExpressions(MutatingScope $scope, SpecifiedTypes $specifiedTypes): SpecifiedTypes
+	{
+		$sureTypes = $specifiedTypes->getSureTypes();
+		$specifiedExpressions = [];
+		foreach ($sureTypes as $exprString => [$expr, $type]) {
+			$specifiedExpressions[$exprString] = ExpressionTypeHolder::createYes($expr, $type);
+		}
+
+		if (count($specifiedExpressions) === 0) {
+			return $specifiedTypes;
+		}
+
+		$additionalSureTypes = [];
+		foreach ($scope->getConditionalExpressions() as $conditionalExprString => $conditionalExpressions) {
+			foreach ($conditionalExpressions as $conditionalExpression) {
+				foreach ($conditionalExpression->getConditionExpressionTypeHolders() as $holderExprString => $conditionalTypeHolder) {
+					if (!array_key_exists($holderExprString, $specifiedExpressions) || !$specifiedExpressions[$holderExprString]->equals($conditionalTypeHolder)) {
+						continue 2;
+					}
+				}
+
+				$holder = $conditionalExpression->getTypeHolder();
+				if (isset($additionalSureTypes[$conditionalExprString])) {
+					$additionalSureTypes[$conditionalExprString] = [
+						$holder->getExpr(),
+						TypeCombinator::intersect($additionalSureTypes[$conditionalExprString][1], $holder->getType()),
+					];
+				} else {
+					$additionalSureTypes[$conditionalExprString] = [$holder->getExpr(), $holder->getType()];
+				}
+			}
+		}
+
+		if (count($additionalSureTypes) === 0) {
+			return $specifiedTypes;
+		}
+
+		foreach ($additionalSureTypes as $additionalExprString => [$additionalExpr, $additionalType]) {
+			if (isset($sureTypes[$additionalExprString])) {
+				$sureTypes[$additionalExprString] = [$additionalExpr, TypeCombinator::union($sureTypes[$additionalExprString][1], $additionalType)];
+			} else {
+				$sureTypes[$additionalExprString] = [$additionalExpr, $additionalType];
+			}
+		}
+
+		$result = new SpecifiedTypes($sureTypes, $specifiedTypes->getSureNotTypes());
+		if ($specifiedTypes->shouldOverwrite()) {
+			$result = $result->setAlwaysOverwriteTypes();
+		}
+
+		return $result->setRootExpr($specifiedTypes->getRootExpr());
+	}
+
 	/**
 	 * @return array{Expr, ConstantScalarType, Type}|null
 	 */
diff --git a/tests/PHPStan/Analyser/nsrt/bug-7716.php b/tests/PHPStan/Analyser/nsrt/bug-7716.php
index fca0a7cfd8a..63280c3b466 100644
--- a/tests/PHPStan/Analyser/nsrt/bug-7716.php
+++ b/tests/PHPStan/Analyser/nsrt/bug-7716.php
@@ -15,7 +15,7 @@ public function sayHello(array $array): int
 		$hasBar = isset($array['bar']) && $array['bar'] > 1;
 
 		if ($hasFoo) {
-			assertType('array{foo?: int, bar?: int}', $array);
+			assertType('array{foo: int, bar?: int}', $array);
 			assertType('int<2, max>', $array['foo']);
 			return $array['foo'];
 		}
@@ -44,7 +44,7 @@ public function sayHello2(array $array): int
 		}
 
 		if ($hasBar) {
-			assertType('array{foo?: int, bar?: int}', $array);
+			assertType('array{foo?: int, bar: int}', $array);
 			assertType('int<2, max>', $array['bar']);
 			return $array['bar'];
 		}
diff --git a/tests/PHPStan/Analyser/nsrt/bug-9519.php b/tests/PHPStan/Analyser/nsrt/bug-9519.php
new file mode 100644
index 00000000000..7a972d27232
--- /dev/null
+++ b/tests/PHPStan/Analyser/nsrt/bug-9519.php
@@ -0,0 +1,87 @@
+<?php declare(strict_types = 1);
+
+namespace Bug9519;
+
+use function PHPStan\Testing\assertType;
+
+class ClassA {
+	public function sayHello(): void
+	{
+		echo 'Hello';
+	}
+}
+
+class ClassB {
+	public function sayHello(): void
+	{
+		echo 'Hello';
+	}
+}
+
+function test1(mixed $obj): void {
+	$isA = $obj instanceof ClassA;
+	$isB = $obj instanceof ClassB;
+
+	if ($isA || $isB) {
+		assertType('Bug9519\ClassA|Bug9519\ClassB', $obj);
+	}
+}
+
+function test2(mixed $obj): void {
+	// Direct instanceof in condition should work (and already does)
+	if (($obj instanceof ClassA) || ($obj instanceof ClassB)) {
+		assertType('Bug9519\ClassA|Bug9519\ClassB', $obj);
+	}
+}
+
+function test3(mixed $obj): void {
+	$isA = $obj instanceof ClassA;
+	$isB = $obj instanceof ClassB;
+
+	if ($isA) {
+		assertType('Bug9519\ClassA', $obj);
+	}
+
+	if ($isB) {
+		assertType('Bug9519\ClassB', $obj);
+	}
+}
+
+interface SomeInterface {
+	public function test(): void;
+}
+
+class ObjectClass {
+}
+
+class OtherClass extends ObjectClass {
+}
+
+/**
+ * @template T of object
+ * @param class-string<T> $class_name
+ * @return T
+ */
+function getObject(string $class_name): object {
+	return new $class_name;
+}
+
+function test4(): void {
+	$obj = getObject(ObjectClass::class);
+	$is_other = $obj instanceof OtherClass;
+	$is_interface = $obj instanceof SomeInterface;
+
+	if ($is_interface) {
+		assertType('Bug9519\ObjectClass&Bug9519\SomeInterface', $obj);
+	}
+}
+
+function test5(): void {
+	$obj = getObject(ObjectClass::class);
+	$is_interface = $obj instanceof SomeInterface;
+	$is_other = $obj instanceof OtherClass;
+
+	if ($is_interface) {
+		assertType('Bug9519\ObjectClass&Bug9519\SomeInterface', $obj);
+	}
+}
diff --git a/tests/PHPStan/Analyser/nsrt/multi-assign.php b/tests/PHPStan/Analyser/nsrt/multi-assign.php
index ab4e4de1cf8..6a2b4a5f645 100644
--- a/tests/PHPStan/Analyser/nsrt/multi-assign.php
+++ b/tests/PHPStan/Analyser/nsrt/multi-assign.php
@@ -55,12 +55,12 @@ function (bool $b): void {
 function (bool $b): void {
 	$foo = $bar = $baz = $b;
 	if ($bar) {
-		assertType('bool', $b);
+		assertType('true', $b);
 		assertType('bool', $foo);
 		assertType('true', $bar);
 		assertType('bool', $baz);
 	} else {
-		assertType('bool', $b);
+		assertType('false', $b);
 		assertType('bool', $foo);
 		assertType('false', $bar);
 		assertType('bool', $baz);
@@ -70,12 +70,12 @@ function (bool $b): void {
 function (bool $b): void {
 	$foo = $bar = $baz = $b;
 	if ($baz) {
-		assertType('bool', $b);
+		assertType('true', $b);
 		assertType('bool', $foo);
 		assertType('bool', $bar);
 		assertType('true', $baz);
 	} else {
-		assertType('bool', $b);
+		assertType('false', $b);
 		assertType('bool', $foo);
 		assertType('bool', $bar);
 		assertType('false', $baz);