diff --git a/src/Type/Php/ReplaceFunctionsDynamicReturnTypeExtension.php b/src/Type/Php/ReplaceFunctionsDynamicReturnTypeExtension.php
index 18a66da75c..c80c10d9c0 100644
--- a/src/Type/Php/ReplaceFunctionsDynamicReturnTypeExtension.php
+++ b/src/Type/Php/ReplaceFunctionsDynamicReturnTypeExtension.php
@@ -6,6 +6,7 @@
 use PHPStan\Analyser\Scope;
 use PHPStan\Reflection\FunctionReflection;
 use PHPStan\Reflection\ParametersAcceptorSelector;
+use PHPStan\Type\Accessory\AccessoryLowercaseStringType;
 use PHPStan\Type\Accessory\AccessoryNonEmptyStringType;
 use PHPStan\Type\Accessory\AccessoryNonFalsyStringType;
 use PHPStan\Type\Constant\ConstantArrayTypeBuilder;
@@ -82,17 +83,26 @@ private function getPreliminarilyResolvedTypeFromFunctionCall(
 			return TypeUtils::toBenevolentUnion($defaultReturnType);
 		}
 
-		if ($subjectArgumentType->isNonEmptyString()->yes() && array_key_exists($functionReflection->getName(), self::FUNCTIONS_REPLACE_POSITION)) {
+		if (array_key_exists($functionReflection->getName(), self::FUNCTIONS_REPLACE_POSITION)) {
 			$replaceArgumentPosition = self::FUNCTIONS_REPLACE_POSITION[$functionReflection->getName()];
 
 			if (count($functionCall->getArgs()) > $replaceArgumentPosition) {
 				$replaceArgumentType = $scope->getType($functionCall->getArgs()[$replaceArgumentPosition]->value);
 
+				$accessories = [];
 				if ($subjectArgumentType->isNonFalsyString()->yes() && $replaceArgumentType->isNonFalsyString()->yes()) {
-					return new IntersectionType([new StringType(), new AccessoryNonFalsyStringType()]);
+					$accessories[] = new AccessoryNonFalsyStringType();
+				} elseif ($subjectArgumentType->isNonEmptyString()->yes() && $replaceArgumentType->isNonEmptyString()->yes()) {
+					$accessories[] = new AccessoryNonEmptyStringType();
 				}
-				if ($replaceArgumentType->isNonEmptyString()->yes()) {
-					return new IntersectionType([new StringType(), new AccessoryNonEmptyStringType()]);
+
+				if ($subjectArgumentType->isLowercaseString()->yes() && $replaceArgumentType->isLowercaseString()->yes()) {
+					$accessories[] = new AccessoryLowercaseStringType();
+				}
+
+				if (count($accessories) > 0) {
+					$accessories[] = new StringType();
+					return new IntersectionType($accessories);
 				}
 			}
 		}
diff --git a/tests/PHPStan/Analyser/LegacyNodeScopeResolverTest.php b/tests/PHPStan/Analyser/LegacyNodeScopeResolverTest.php
index 0cb675d14b..9860a71f59 100644
--- a/tests/PHPStan/Analyser/LegacyNodeScopeResolverTest.php
+++ b/tests/PHPStan/Analyser/LegacyNodeScopeResolverTest.php
@@ -7414,7 +7414,7 @@ public function dataReplaceFunctions(): array
 	{
 		return [
 			[
-				'non-falsy-string',
+				'lowercase-string&non-falsy-string',
 				'$expectedString',
 			],
 			[
@@ -7422,7 +7422,7 @@ public function dataReplaceFunctions(): array
 				'$expectedString2',
 			],
 			[
-				'non-falsy-string|null',
+				'(lowercase-string&non-falsy-string)|null',
 				'$anotherExpectedString',
 			],
 			[
diff --git a/tests/PHPStan/Analyser/nsrt/isset-coalesce-empty-type.php b/tests/PHPStan/Analyser/nsrt/isset-coalesce-empty-type.php
index ef291855ed..a38116b682 100644
--- a/tests/PHPStan/Analyser/nsrt/isset-coalesce-empty-type.php
+++ b/tests/PHPStan/Analyser/nsrt/isset-coalesce-empty-type.php
@@ -472,7 +472,7 @@ function coalesce()
 
 		assertType('int<0, max>', rand() ?? false);
 
-		assertType('0|string', preg_replace('', '', '') ?? 0);
+		assertType('0|lowercase-string', preg_replace('', '', '') ?? 0);
 
 		$foo = new FooCoalesce();
 
diff --git a/tests/PHPStan/Analyser/nsrt/lowercase-string-replace.php b/tests/PHPStan/Analyser/nsrt/lowercase-string-replace.php
new file mode 100644
index 0000000000..c9546ba2d0
--- /dev/null
+++ b/tests/PHPStan/Analyser/nsrt/lowercase-string-replace.php
@@ -0,0 +1,42 @@
+<?php
+
+namespace LowercaseStringReplace;
+
+use function PHPStan\Testing\assertType;
+
+class ReplaceStrings
+{
+
+	/**
+	 * @param string $s
+	 * @param lowercase-string $ls
+	 */
+	public function doFoo(string $s, string $ls): void
+	{
+		assertType('lowercase-string', str_replace($s, $ls, $ls));
+		assertType('string', str_replace($s, $s, $ls));
+		assertType('string', str_replace($s, $ls, $s));
+		assertType('lowercase-string', str_replace($ls, $ls, $ls));
+		assertType('string', str_replace($ls, $s, $ls));
+		assertType('string', str_replace($ls, $ls, $s));
+
+		assertType('lowercase-string', str_ireplace($s, $ls, $ls));
+		assertType('string', str_ireplace($s, $s, $ls));
+		assertType('string', str_ireplace($s, $ls, $s));
+		assertType('lowercase-string', str_ireplace($ls, $ls, $ls));
+		assertType('string', str_ireplace($ls, $s, $ls));
+		assertType('string', str_ireplace($ls, $ls, $s));
+
+		assertType('lowercase-string|null', preg_replace($s, $ls, $ls));
+		assertType('string|null', preg_replace($s, $s, $ls));
+		assertType('string|null', preg_replace($s, $ls, $s));
+		assertType('lowercase-string|null', preg_replace($ls, $ls, $ls));
+		assertType('string|null', preg_replace($ls, $s, $ls));
+		assertType('string|null', preg_replace($ls, $ls, $s));
+
+		assertType('lowercase-string', substr_replace($ls, $ls, 1));
+		assertType('string', substr_replace($s, $ls, 1));
+		assertType('string', substr_replace($ls, $s, 1));
+		assertType('string', substr_replace($s, $s, 1));
+	}
+}