diff --git a/src/Type/Php/SprintfFunctionDynamicReturnTypeExtension.php b/src/Type/Php/SprintfFunctionDynamicReturnTypeExtension.php
index 7bb7e2da26..dc30f2afdd 100644
--- a/src/Type/Php/SprintfFunctionDynamicReturnTypeExtension.php
+++ b/src/Type/Php/SprintfFunctionDynamicReturnTypeExtension.php
@@ -8,9 +8,11 @@
 use PHPStan\Internal\CombinationsHelper;
 use PHPStan\Reflection\FunctionReflection;
 use PHPStan\Reflection\InitializerExprTypeResolver;
+use PHPStan\Type\Accessory\AccessoryLowercaseStringType;
 use PHPStan\Type\Accessory\AccessoryNonEmptyStringType;
 use PHPStan\Type\Accessory\AccessoryNonFalsyStringType;
 use PHPStan\Type\Accessory\AccessoryNumericStringType;
+use PHPStan\Type\Accessory\AccessoryType;
 use PHPStan\Type\Constant\ConstantIntegerType;
 use PHPStan\Type\Constant\ConstantStringType;
 use PHPStan\Type\DynamicFunctionReturnTypeExtension;
@@ -60,6 +62,13 @@ public function getTypeFromFunctionCall(
 		$formatType = $scope->getType($args[0]->value);
 		$formatStrings = $formatType->getConstantStrings();
 
+		$isLowercase = $formatType->isLowercaseString()->yes() && $this->allValuesSatisfies(
+			$functionReflection,
+			$scope,
+			$args,
+			static fn (Type $type): bool => $type->toString()->isLowercaseString()->yes()
+		);
+
 		$singlePlaceholderEarlyReturn = null;
 		$allPatternsNonEmpty = count($formatStrings) !== 0;
 		$allPatternsNonFalsy = count($formatStrings) !== 0;
@@ -130,10 +139,10 @@ public function getTypeFromFunctionCall(
 
 					$singlePlaceholderEarlyReturn = $checkArgType->toString();
 				} elseif ($matches['specifier'] !== 's') {
-					$singlePlaceholderEarlyReturn = new IntersectionType([
-						new StringType(),
+					$singlePlaceholderEarlyReturn = $this->getStringReturnType(
 						new AccessoryNumericStringType(),
-					]);
+						$isLowercase,
+					);
 				}
 
 				continue;
@@ -148,10 +157,7 @@ public function getTypeFromFunctionCall(
 		}
 
 		if ($allPatternsNonFalsy) {
-			return new IntersectionType([
-				new StringType(),
-				new AccessoryNonFalsyStringType(),
-			]);
+			return $this->getStringReturnType(new AccessoryNonFalsyStringType(), $isLowercase);
 		}
 
 		$isNonEmpty = $allPatternsNonEmpty;
@@ -165,13 +171,10 @@ public function getTypeFromFunctionCall(
 		}
 
 		if ($isNonEmpty) {
-			return new IntersectionType([
-				new StringType(),
-				new AccessoryNonEmptyStringType(),
-			]);
+			return $this->getStringReturnType(new AccessoryNonEmptyStringType(), $isLowercase);
 		}
 
-		return new StringType();
+		return $this->getStringReturnType(null, $isLowercase);
 	}
 
 	/**
@@ -347,4 +350,23 @@ private function getConstantType(array $args, FunctionReflection $functionReflec
 		return TypeCombinator::union(...$returnTypes);
 	}
 
+	private function getStringReturnType(?AccessoryType $accessoryType, bool $isLowercase): Type
+	{
+		$accessoryTypes = [];
+		if ($accessoryType !== null) {
+			$accessoryTypes[] = $accessoryType;
+		}
+		if ($isLowercase) {
+			$accessoryTypes[] = new AccessoryLowercaseStringType();
+		}
+
+		if (count($accessoryTypes) === 0) {
+			return new StringType();
+		}
+
+		$accessoryTypes[] = new StringType();
+
+		return new IntersectionType($accessoryTypes);
+	}
+
 }
diff --git a/tests/PHPStan/Analyser/nsrt/bug-11201.php b/tests/PHPStan/Analyser/nsrt/bug-11201.php
index 74a41fa235..202e5b1700 100644
--- a/tests/PHPStan/Analyser/nsrt/bug-11201.php
+++ b/tests/PHPStan/Analyser/nsrt/bug-11201.php
@@ -53,4 +53,4 @@ function returnsBool(): bool {
 assertType("'                   1'", $s);
 
 $s = sprintf('%20s', returnsBool());
-assertType("non-falsy-string", $s);
+assertType("lowercase-string&non-falsy-string", $s);
diff --git a/tests/PHPStan/Analyser/nsrt/bug-7387.php b/tests/PHPStan/Analyser/nsrt/bug-7387.php
index cfb1a97642..909de25e1f 100644
--- a/tests/PHPStan/Analyser/nsrt/bug-7387.php
+++ b/tests/PHPStan/Analyser/nsrt/bug-7387.php
@@ -107,11 +107,11 @@ public function escapedPercent(int $i) {
 
 	public function vsprintf(array $array)
 	{
-		assertType('numeric-string', vsprintf("%4d", explode('-', '1988-8-1')));
+		assertType('lowercase-string&numeric-string', vsprintf("%4d", explode('-', '1988-8-1')));
 		assertType('numeric-string', vsprintf("%4d", $array));
-		assertType('numeric-string', vsprintf("%4d", ['123']));
+		assertType('lowercase-string&numeric-string', vsprintf("%4d", ['123']));
 		assertType('\'123\'', vsprintf("%s", ['123']));
 		// too many arguments.. php silently allows it
-		assertType('numeric-string', vsprintf("%4d", ['123', '456']));
+		assertType('lowercase-string&numeric-string', vsprintf("%4d", ['123', '456']));
 	}
 }
diff --git a/tests/PHPStan/Analyser/nsrt/dynamic-sprintf.php b/tests/PHPStan/Analyser/nsrt/dynamic-sprintf.php
index ec25be47cd..3555613fe0 100644
--- a/tests/PHPStan/Analyser/nsrt/dynamic-sprintf.php
+++ b/tests/PHPStan/Analyser/nsrt/dynamic-sprintf.php
@@ -33,7 +33,7 @@ public function integerRange(int $a, string $b): void
 	 */
 	public function tooBigRange(int $a, string $b): void
 	{
-		assertType("non-falsy-string", sprintf('%d %s', $a, $b));
+		assertType("lowercase-string&non-falsy-string", sprintf('%d %s', $a, $b));
 	}
 
 }
diff --git a/tests/PHPStan/Analyser/nsrt/lowercase-string-sprintf.php b/tests/PHPStan/Analyser/nsrt/lowercase-string-sprintf.php
new file mode 100644
index 0000000000..db7127a15c
--- /dev/null
+++ b/tests/PHPStan/Analyser/nsrt/lowercase-string-sprintf.php
@@ -0,0 +1,116 @@
+<?php
+
+namespace LowercaseStringSprintf;
+
+use function PHPStan\Testing\assertType;
+
+class Foo
+{
+
+	/**
+	 * @param lowercase-string $lowercase
+	 * @param lowercase-string&non-empty-string $nonEmptyLowercase
+	 * @param lowercase-string&non-falsy-string $nonFalsyLowercase
+	 */
+	public function doSprintf(
+		string $string,
+		string $lowercase,
+		string $nonEmptyLowercase,
+		string $nonFalsyLowercase,
+		bool $bool
+	): void {
+		$format = $bool ? 'Foo 1 %s' : 'Foo 2 %s';
+		$formatLower = $bool ? 'foo 1 %s' : 'foo 2 %s';
+		$constant = $bool ? 'A' : 'B';
+		$constantLower = $bool ? 'a' : 'b';
+
+		assertType("'A'|'B'", sprintf('%s', $constant));
+		assertType("'0'", sprintf('%d', $constant));
+		assertType("'Foo 1 A'|'Foo 1 B'|'Foo 2 A'|'Foo 2 B'", sprintf($format, $constant));
+		assertType("'foo 1 A'|'foo 1 B'|'foo 2 A'|'foo 2 B'", sprintf($formatLower, $constant));
+		assertType('string', sprintf($lowercase, $constant));
+		assertType('string', sprintf($string, $constant));
+
+		assertType("'a'|'b'", sprintf('%s', $constantLower));
+		assertType("'0'", sprintf('%d', $constantLower));
+		assertType("'Foo 1 a'|'Foo 1 b'|'Foo 2 a'|'Foo 2 b'", sprintf($format, $constantLower));
+		assertType("'foo 1 a'|'foo 1 b'|'foo 2 a'|'foo 2 b'", sprintf($formatLower, $constantLower));
+		assertType('lowercase-string', sprintf($lowercase, $constantLower));
+		assertType('string', sprintf($string, $constantLower));
+
+		assertType('lowercase-string', sprintf('%s', $lowercase));
+		assertType('lowercase-string&numeric-string', sprintf('%d', $lowercase));
+		assertType('non-falsy-string', sprintf($format, $lowercase));
+		assertType('lowercase-string&non-falsy-string', sprintf($formatLower, $lowercase));
+		assertType('lowercase-string', sprintf($lowercase, $lowercase));
+		assertType('string', sprintf($string, $lowercase));
+
+		assertType('lowercase-string&non-empty-string', sprintf('%s', $nonEmptyLowercase));
+		assertType('lowercase-string&numeric-string', sprintf('%d', $nonEmptyLowercase));
+		assertType('non-falsy-string', sprintf($format, $nonEmptyLowercase));
+		assertType('lowercase-string&non-falsy-string', sprintf($formatLower, $nonEmptyLowercase));
+		assertType('lowercase-string&non-empty-string', sprintf($nonEmptyLowercase, $nonEmptyLowercase));
+		assertType('string', sprintf($string, $nonEmptyLowercase));
+
+		assertType('lowercase-string&non-falsy-string', sprintf('%s', $nonFalsyLowercase));
+		assertType('lowercase-string&numeric-string', sprintf('%d', $nonFalsyLowercase));
+		assertType('non-falsy-string', sprintf($format, $nonFalsyLowercase));
+		assertType('lowercase-string&non-falsy-string', sprintf($formatLower, $nonFalsyLowercase));
+		assertType('lowercase-string&non-empty-string', sprintf($nonFalsyLowercase, $nonFalsyLowercase));
+		assertType('string', sprintf($string, $nonFalsyLowercase));
+	}
+
+	/**
+	 * @param lowercase-string $lowercase
+	 * @param lowercase-string&non-empty-string $nonEmptyLowercase
+	 * @param lowercase-string&non-falsy-string $nonFalsyLowercase
+	 */
+	public function doVSprintf(
+		string $string,
+		string $lowercase,
+		string $nonEmptyLowercase,
+		string $nonFalsyLowercase,
+		bool $bool
+	): void {
+		$format = $bool ? 'Foo 1 %s' : 'Foo 2 %s';
+		$formatLower = $bool ? 'foo 1 %s' : 'foo 2 %s';
+		$constant = $bool ? 'A' : 'B';
+		$constantLower = $bool ? 'a' : 'b';
+
+		assertType("'A'|'B'", vsprintf('%s', [$constant]));
+		assertType('numeric-string', vsprintf('%d', [$constant]));
+		assertType('non-falsy-string', vsprintf($format, [$constant]));
+		assertType('non-falsy-string', vsprintf($formatLower, [$constant]));
+		assertType('string', vsprintf($lowercase, [$constant]));
+		assertType('string', vsprintf($string, [$constant]));
+
+		assertType("'a'|'b'", vsprintf('%s', [$constantLower]));
+		assertType('lowercase-string&numeric-string', vsprintf('%d', [$constantLower]));
+		assertType('non-falsy-string', vsprintf($format, [$constantLower]));
+		assertType('lowercase-string&non-falsy-string', vsprintf($formatLower, [$constantLower]));
+		assertType('lowercase-string', vsprintf($lowercase, [$constantLower]));
+		assertType('string', vsprintf($string, [$constantLower]));
+
+		assertType('lowercase-string', vsprintf('%s', [$lowercase]));
+		assertType('lowercase-string&numeric-string', vsprintf('%d', [$lowercase]));
+		assertType('non-falsy-string', vsprintf($format, [$lowercase]));
+		assertType('lowercase-string&non-falsy-string', vsprintf($formatLower, [$lowercase]));
+		assertType('lowercase-string', vsprintf($lowercase, [$lowercase]));
+		assertType('string', vsprintf($string, [$lowercase]));
+
+		assertType('lowercase-string&non-empty-string', vsprintf('%s', [$nonEmptyLowercase]));
+		assertType('lowercase-string&numeric-string', vsprintf('%d', [$nonEmptyLowercase]));
+		assertType('non-falsy-string', vsprintf($format, [$nonEmptyLowercase]));
+		assertType('lowercase-string&non-falsy-string', vsprintf($formatLower, [$nonEmptyLowercase]));
+		assertType('lowercase-string&non-empty-string', vsprintf($nonEmptyLowercase, [$nonEmptyLowercase]));
+		assertType('string', vsprintf($string, [$nonEmptyLowercase]));
+
+		assertType('lowercase-string&non-falsy-string', vsprintf('%s', [$nonFalsyLowercase]));
+		assertType('lowercase-string&numeric-string', vsprintf('%d', [$nonFalsyLowercase]));
+		assertType('non-falsy-string', vsprintf($format, [$nonFalsyLowercase]));
+		assertType('lowercase-string&non-falsy-string', vsprintf($formatLower, [$nonFalsyLowercase]));
+		assertType('lowercase-string&non-empty-string', vsprintf($nonFalsyLowercase, [$nonFalsyLowercase]));
+		assertType('string', vsprintf($string, [$nonFalsyLowercase]));
+	}
+
+}