diff --git a/src/Type/Php/ArrayKeyExistsFunctionTypeSpecifyingExtension.php b/src/Type/Php/ArrayKeyExistsFunctionTypeSpecifyingExtension.php
index c9de826666..714768a8b9 100644
--- a/src/Type/Php/ArrayKeyExistsFunctionTypeSpecifyingExtension.php
+++ b/src/Type/Php/ArrayKeyExistsFunctionTypeSpecifyingExtension.php
@@ -66,13 +66,19 @@ public function specifyTypes(
 			&& !$keyType instanceof ConstantStringType
 		) {
 			if ($context->true()) {
-				if ($arrayType->isIterableAtLeastOnce()->no()) {
-					return $this->typeSpecifier->create(
+				$specifiedTypes = new SpecifiedTypes();
+
+				if (count($keyType->getConstantScalarTypes()) <= 1) {
+					$specifiedTypes = $specifiedTypes->unionWith($this->typeSpecifier->create(
 						$array,
 						new NonEmptyArrayType(),
 						$context,
 						$scope,
-					);
+					));
+				}
+
+				if ($arrayType->isIterableAtLeastOnce()->no()) {
+					return $specifiedTypes;
 				}
 
 				$arrayKeyType = $arrayType->getIterableKeyType();
@@ -82,12 +88,12 @@ public function specifyTypes(
 					$arrayKeyType = TypeCombinator::union($arrayKeyType, $arrayKeyType->toString());
 				}
 
-				$specifiedTypes = $this->typeSpecifier->create(
+				$specifiedTypes = $specifiedTypes->unionWith($this->typeSpecifier->create(
 					$key,
 					$arrayKeyType,
 					$context,
 					$scope,
-				);
+				));
 
 				$arrayDimFetch = new ArrayDimFetch(
 					$array,
diff --git a/tests/PHPStan/Analyser/nsrt/bug13674a.php b/tests/PHPStan/Analyser/nsrt/bug13674a.php
new file mode 100644
index 0000000000..c1750e89da
--- /dev/null
+++ b/tests/PHPStan/Analyser/nsrt/bug13674a.php
@@ -0,0 +1,29 @@
+<?php
+
+namespace Bug13674a;
+
+use function PHPStan\Testing\assertType;
+
+class HelloWorld
+{
+	/**
+	 * @param array<int> $arrayA
+	 * @param list<int> $listA
+	 */
+	public function sayHello($arrayA, $listA, int $i): void
+	{
+		if (array_key_exists($i, $arrayA)) {
+			assertType('non-empty-array<int>', $arrayA);
+		} else {
+			assertType('array<int>', $arrayA);
+		}
+		assertType('array<int>', $arrayA);
+
+		if (array_key_exists($i, $listA)) {
+			assertType('non-empty-list<int>', $listA);
+		} else {
+			assertType('list<int>', $listA);
+		}
+		assertType('list<int>', $listA);
+	}
+}
diff --git a/tests/PHPStan/Rules/Arrays/NonexistentOffsetInArrayDimFetchRuleTest.php b/tests/PHPStan/Rules/Arrays/NonexistentOffsetInArrayDimFetchRuleTest.php
index 471a1a1b01..b18e1aa4f3 100644
--- a/tests/PHPStan/Rules/Arrays/NonexistentOffsetInArrayDimFetchRuleTest.php
+++ b/tests/PHPStan/Rules/Arrays/NonexistentOffsetInArrayDimFetchRuleTest.php
@@ -406,6 +406,16 @@ public function testBug7000(): void
 		]);
 	}
 
+	public function testBug7000b(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-7000b.php'], [
+			[
+				"Offset 'require'|'require-dev' might not exist on array{require?: array<string, string>, require-dev?: array<string, string>}.",
+				16,
+			],
+		]);
+	}
+
 	public function testBug6508(): void
 	{
 		$this->analyse([__DIR__ . '/data/bug-6508.php'], []);
diff --git a/tests/PHPStan/Rules/Arrays/data/bug-7000b.php b/tests/PHPStan/Rules/Arrays/data/bug-7000b.php
new file mode 100644
index 0000000000..2789458ab3
--- /dev/null
+++ b/tests/PHPStan/Rules/Arrays/data/bug-7000b.php
@@ -0,0 +1,20 @@
+<?php declare(strict_types = 1);
+
+namespace Bug7000b;
+
+class Foo
+{
+	public function doBar(): void
+	{
+		/** @var array{require?: array<string, string>, require-dev?: array<string, string>} $composer */
+		$composer = array();
+		/** @var 'require'|'require-dev' $foo */
+		$foo = '';
+		foreach (array('require', 'require-dev') as $linkType) {
+			if (array_key_exists($linkType, $composer)) {
+				foreach ($composer[$linkType] as $x) {} // should not report error
+				foreach ($composer[$foo] as $x) {} // should report error. It can be $linkType = 'require', $foo = 'require-dev'
+			}
+		}
+	}
+}
diff --git a/tests/PHPStan/Rules/Arrays/data/slevomat-foreach-array-key-exists-bug.php b/tests/PHPStan/Rules/Arrays/data/slevomat-foreach-array-key-exists-bug.php
index 0588be365b..08ee797f08 100644
--- a/tests/PHPStan/Rules/Arrays/data/slevomat-foreach-array-key-exists-bug.php
+++ b/tests/PHPStan/Rules/Arrays/data/slevomat-foreach-array-key-exists-bug.php
@@ -15,7 +15,7 @@ public function doFoo(array $percentageIntervals, array $changes): void
 				if ($percentageInterval->isInInterval((float) $changeInPercents)) {
 					$key = $percentageInterval->getFormatted();
 					if (array_key_exists($key, $intervalResults)) {
-						assertType('array<array{itemsCount: mixed, interval: mixed}>', $intervalResults);
+						assertType('non-empty-array<array{itemsCount: mixed, interval: mixed}>', $intervalResults);
 						assertType('array{itemsCount: mixed, interval: mixed}', $intervalResults[$key]);
 						$intervalResults[$key]['itemsCount'] += $itemsCount;
 						assertType('non-empty-array<array{itemsCount: (array|float|int), interval: mixed}>', $intervalResults);