diff --git a/src/Analyser/TypeSpecifier.php b/src/Analyser/TypeSpecifier.php
index 52b3d76d45..1e58feac38 100644
--- a/src/Analyser/TypeSpecifier.php
+++ b/src/Analyser/TypeSpecifier.php
@@ -1087,10 +1087,7 @@ private function specifyTypesForCountFuncCall(
 			if (
 				$sizeType instanceof ConstantIntegerType
 				&& $sizeType->getValue() < ConstantArrayTypeBuilder::ARRAY_COUNT_LIMIT
-				&& (
-					$isList->yes()
-					|| $isConstantArray->yes() && $arrayType->getKeyType()->isSuperTypeOf(IntegerRangeType::fromInterval(0, $sizeType->getValue() - 1))->yes()
-				)
+				&& $arrayType->getKeyType()->isSuperTypeOf(IntegerRangeType::fromInterval(0, $sizeType->getValue() - 1))->yes()
 			) {
 				// turn optional offsets non-optional
 				$valueTypesBuilder = ConstantArrayTypeBuilder::createEmpty();
@@ -1105,21 +1102,23 @@ private function specifyTypesForCountFuncCall(
 			if (
 				$sizeType instanceof IntegerRangeType
 				&& $sizeType->getMin() !== null
-				&& (
-					$isList->yes()
-					|| $isConstantArray->yes() && $arrayType->getKeyType()->isSuperTypeOf(IntegerRangeType::fromInterval(0, $sizeType->getMin() - 1))->yes()
-				)
+				&& $sizeType->getMin() < ConstantArrayTypeBuilder::ARRAY_COUNT_LIMIT
+				&& $arrayType->getKeyType()->isSuperTypeOf(IntegerRangeType::fromInterval(0, ($sizeType->getMax() ?? $sizeType->getMin()) - 1))->yes()
 			) {
+				$builderData = [];
 				// turn optional offsets non-optional
-				$valueTypesBuilder = ConstantArrayTypeBuilder::createEmpty();
 				for ($i = 0; $i < $sizeType->getMin(); $i++) {
 					$offsetType = new ConstantIntegerType($i);
-					$valueTypesBuilder->setOffsetValueType($offsetType, $arrayType->getOffsetValueType($offsetType));
+					$builderData[] = [$offsetType, $arrayType->getOffsetValueType($offsetType), false];
 				}
 				if ($sizeType->getMax() !== null) {
+					if ($sizeType->getMax() - $sizeType->getMin() > ConstantArrayTypeBuilder::ARRAY_COUNT_LIMIT) {
+						$resultTypes[] = $arrayType;
+						continue;
+					}
 					for ($i = $sizeType->getMin(); $i < $sizeType->getMax(); $i++) {
 						$offsetType = new ConstantIntegerType($i);
-						$valueTypesBuilder->setOffsetValueType($offsetType, $arrayType->getOffsetValueType($offsetType), true);
+						$builderData[] = [$offsetType, $arrayType->getOffsetValueType($offsetType), true];
 					}
 				} elseif ($arrayType->isConstantArray()->yes()) {
 					for ($i = $sizeType->getMin();; $i++) {
@@ -1128,14 +1127,24 @@ private function specifyTypesForCountFuncCall(
 						if ($hasOffset->no()) {
 							break;
 						}
-						$valueTypesBuilder->setOffsetValueType($offsetType, $arrayType->getOffsetValueType($offsetType), !$hasOffset->yes());
+						$builderData[] = [$offsetType, $arrayType->getOffsetValueType($offsetType), !$hasOffset->yes()];
 					}
 				} else {
 					$resultTypes[] = TypeCombinator::intersect($arrayType, new NonEmptyArrayType());
 					continue;
 				}
 
-				$resultTypes[] = $valueTypesBuilder->getArray();
+				if (count($builderData) > ConstantArrayTypeBuilder::ARRAY_COUNT_LIMIT) {
+					$resultTypes[] = $arrayType;
+					continue;
+				}
+
+				$builder = ConstantArrayTypeBuilder::createEmpty();
+				foreach ($builderData as [$offsetType, $valueType, $optional]) {
+					$builder->setOffsetValueType($offsetType, $valueType, $optional);
+				}
+
+				$resultTypes[] = $builder->getArray();
 				continue;
 			}
 
diff --git a/tests/PHPStan/Analyser/AnalyserIntegrationTest.php b/tests/PHPStan/Analyser/AnalyserIntegrationTest.php
index e7678b1449..d515fb2379 100644
--- a/tests/PHPStan/Analyser/AnalyserIntegrationTest.php
+++ b/tests/PHPStan/Analyser/AnalyserIntegrationTest.php
@@ -1542,6 +1542,12 @@ public function testBug12159(): void
 		$this->assertNoErrors($errors);
 	}
 
+	public function testBug12787(): void
+	{
+		$errors = $this->runAnalyse(__DIR__ . '/data/bug-12787.php');
+		$this->assertNoErrors($errors);
+	}
+
 	/**
 	 * @param string[]|null $allAnalysedFiles
 	 * @return Error[]
diff --git a/tests/PHPStan/Analyser/data/bug-12787.php b/tests/PHPStan/Analyser/data/bug-12787.php
new file mode 100644
index 0000000000..189d88cc8b
--- /dev/null
+++ b/tests/PHPStan/Analyser/data/bug-12787.php
@@ -0,0 +1,22 @@
+<?php declare(strict_types = 1);
+
+namespace Bug12787;
+
+class HelloWorld
+{
+	protected const MAX_COUNT = 100000000;
+
+	/**
+	 * @return string[]
+	 */
+	public function accumulate(): array
+	{
+		$items = [];
+
+		do {
+			$items[] = 'something';
+		} while (count($items) < self::MAX_COUNT);
+
+		return $items;
+	}
+}
diff --git a/tests/PHPStan/Analyser/nsrt/list-count.php b/tests/PHPStan/Analyser/nsrt/list-count.php
index b5496d324d..b42f0ec8bd 100644
--- a/tests/PHPStan/Analyser/nsrt/list-count.php
+++ b/tests/PHPStan/Analyser/nsrt/list-count.php
@@ -341,12 +341,15 @@ protected function testOptionalKeysInUnionArray($row): void
 
 	/**
 	 * @param array{string}|list{0: int, 1?: string|null, 2?: int|null, 3?: float|null} $row
+	 * @param list<string> $listRow
 	 * @param int<2, 3> $twoOrThree
 	 * @param int<2, max> $twoOrMore
 	 * @param int<min, 3> $maxThree
 	 * @param int<10, 11> $tenOrEleven
+	 * @param int<3, 32> $threeOrMoreInRangeLimit
+	 * @param int<3, 512> $threeOrMoreOverRangeLimit
 	 */
-	protected function testOptionalKeysInUnionListWithIntRange($row, $twoOrThree, $twoOrMore, int $maxThree, $tenOrEleven): void
+	protected function testOptionalKeysInUnionListWithIntRange($row, $listRow, $twoOrThree, $twoOrMore, int $maxThree, $tenOrEleven, $threeOrMoreInRangeLimit, $threeOrMoreOverRangeLimit): void
 	{
 		if (count($row) >= $twoOrThree) {
 			assertType('array{0: int, 1: string|null, 2?: int|null}', $row);
@@ -371,6 +374,30 @@ protected function testOptionalKeysInUnionListWithIntRange($row, $twoOrThree, $t
 		} else {
 			assertType('array{string}|list{0: int, 1?: string|null, 2?: int|null, 3?: float|null}', $row);
 		}
+
+		if (count($row) >= $threeOrMoreInRangeLimit) {
+			assertType('list{0: int, 1?: string|null, 2?: int|null, 3?: float|null}', $row);
+		} else {
+			assertType('array{string}|list{0: int, 1?: string|null, 2?: int|null, 3?: float|null}', $row);
+		}
+
+		if (count($listRow) >= $threeOrMoreInRangeLimit) {
+			assertType('list{0: string, 1: string, 2: string, 3?: string, 4?: string, 5?: string, 6?: string, 7?: string, 8?: string, 9?: string, 10?: string, 11?: string, 12?: string, 13?: string, 14?: string, 15?: string, 16?: string, 17?: string, 18?: string, 19?: string, 20?: string, 21?: string, 22?: string, 23?: string, 24?: string, 25?: string, 26?: string, 27?: string, 28?: string, 29?: string, 30?: string, 31?: string}', $listRow);
+		} else {
+			assertType('list<string>', $listRow);
+		}
+
+		if (count($row) >= $threeOrMoreOverRangeLimit) {
+			assertType('list{0: int, 1?: string|null, 2?: int|null, 3?: float|null}', $row);
+		} else {
+			assertType('array{string}|list{0: int, 1?: string|null, 2?: int|null, 3?: float|null}', $row);
+		}
+
+		if (count($listRow) >= $threeOrMoreOverRangeLimit) {
+			assertType('non-empty-list<string>', $listRow);
+		} else {
+			assertType('list<string>', $listRow);
+		}
 	}
 
 	/**