diff --git a/tests/PHPStan/Analyser/nsrt/more-types.php b/tests/PHPStan/Analyser/nsrt/more-types.php
index f1b742f170e..1f74b7c8c56 100644
--- a/tests/PHPStan/Analyser/nsrt/more-types.php
+++ b/tests/PHPStan/Analyser/nsrt/more-types.php
@@ -17,6 +17,8 @@ class Foo
 	 * @param non-empty-scalar $nonEmptyScalar
 	 * @param empty-scalar $emptyScalar
 	 * @param non-empty-mixed $nonEmptyMixed
+	 * @param lowercase-string $lowercaseString
+	 * @param non-empty-lowercase-string $nonEmptyLowercaseString
 	 */
 	public function doFoo(
 		$pureCallable,
@@ -27,7 +29,9 @@ public function doFoo(
 		$nonEmptyLiteralString,
 		$nonEmptyScalar,
 		$emptyScalar,
-		$nonEmptyMixed
+		$nonEmptyMixed,
+		$lowercaseString,
+		$nonEmptyLowercaseString,
 	): void
 	{
 		assertType('pure-callable(): mixed', $pureCallable);
@@ -39,6 +43,8 @@ public function doFoo(
 		assertType('float|int<min, -1>|int<1, max>|non-falsy-string|true', $nonEmptyScalar);
 		assertType("0|0.0|''|'0'|false", $emptyScalar);
 		assertType("mixed~0|0.0|''|'0'|array{}|false|null", $nonEmptyMixed);
+		assertType('lowercase-string', $lowercaseString);
+		assertType('lowercase-string&non-empty-string', $nonEmptyLowercaseString);
 	}
 
 }
diff --git a/tests/PHPStan/Rules/Comparison/StrictComparisonOfDifferentTypesRuleTest.php b/tests/PHPStan/Rules/Comparison/StrictComparisonOfDifferentTypesRuleTest.php
index 71be1465a4f..f626fc4ec1f 100644
--- a/tests/PHPStan/Rules/Comparison/StrictComparisonOfDifferentTypesRuleTest.php
+++ b/tests/PHPStan/Rules/Comparison/StrictComparisonOfDifferentTypesRuleTest.php
@@ -1052,6 +1052,54 @@ public function testBug10697(): void
 		$this->analyse([__DIR__ . '/data/bug-10697.php'], []);
 	}
 
+	public function testLowercaseString(): void
+	{
+		$errors = [
+			[
+				"Strict comparison using === between lowercase-string and 'AB' will always evaluate to false.",
+				10,
+				'Because the type is coming from a PHPDoc, you can turn off this check by setting <fg=cyan>treatPhpDocTypesAsCertain: false</> in your <fg=cyan>%configurationFile%</>.',
+			],
+			[
+				"Strict comparison using === between 'AB' and lowercase-string will always evaluate to false.",
+				11,
+				'Because the type is coming from a PHPDoc, you can turn off this check by setting <fg=cyan>treatPhpDocTypesAsCertain: false</> in your <fg=cyan>%configurationFile%</>.',
+			],
+			[
+				"Strict comparison using !== between 'AB' and lowercase-string will always evaluate to true.",
+				12,
+				'Because the type is coming from a PHPDoc, you can turn off this check by setting <fg=cyan>treatPhpDocTypesAsCertain: false</> in your <fg=cyan>%configurationFile%</>.',
+			],
+			[
+				"Strict comparison using === between lowercase-string and 'aBc' will always evaluate to false.",
+				15,
+				'Because the type is coming from a PHPDoc, you can turn off this check by setting <fg=cyan>treatPhpDocTypesAsCertain: false</> in your <fg=cyan>%configurationFile%</>.',
+			],
+			[
+				"Strict comparison using !== between lowercase-string and 'aBc' will always evaluate to true.",
+				16,
+				'Because the type is coming from a PHPDoc, you can turn off this check by setting <fg=cyan>treatPhpDocTypesAsCertain: false</> in your <fg=cyan>%configurationFile%</>.',
+			],
+		];
+
+		if (PHP_VERSION_ID < 80000) {
+			$errors[] = [
+				"Strict comparison using === between lowercase-string|false and 'AB' will always evaluate to false.",
+				28,
+				'Because the type is coming from a PHPDoc, you can turn off this check by setting <fg=cyan>treatPhpDocTypesAsCertain: false</> in your <fg=cyan>%configurationFile%</>.',
+			];
+		} else {
+			$errors[] = [
+				"Strict comparison using === between lowercase-string and 'AB' will always evaluate to false.",
+				28,
+				'Because the type is coming from a PHPDoc, you can turn off this check by setting <fg=cyan>treatPhpDocTypesAsCertain: false</> in your <fg=cyan>%configurationFile%</>.',
+			];
+		}
+
+		$this->checkAlwaysTrueStrictComparison = true;
+		$this->analyse([__DIR__ . '/data/lowercase-string.php'], $errors);
+	}
+
 	public function testBug10493(): void
 	{
 		$this->checkAlwaysTrueStrictComparison = true;
diff --git a/tests/PHPStan/Rules/Comparison/data/lowercase-string.php b/tests/PHPStan/Rules/Comparison/data/lowercase-string.php
new file mode 100644
index 00000000000..772939626ab
--- /dev/null
+++ b/tests/PHPStan/Rules/Comparison/data/lowercase-string.php
@@ -0,0 +1,31 @@
+<?php
+
+namespace LowercaseString;
+
+class Foo
+{
+
+	/** @param lowercase-string $s */
+	function doFoo($s) {
+		if ($s === 'AB') {}
+		if ('AB' === $s) {}
+		if ('AB' !== $s) {}
+		if ($s === 'ab') {}
+		if ($s !== 'ab') {}
+		if ($s === 'aBc') {}
+		if ($s !== 'aBc') {}
+		if ($s === '01') {}
+		if ($s === '1e2') {}
+		if ($s === MyClass::myConst) {}
+		if ($s === A_GLOBAL_CONST) {}
+		if (doFoo('hi') === 'AB') {}
+	}
+
+	/** @param lowercase-string $s */
+	function doFoo2($s, int $x, int $y) {
+		$part = substr($s, $x, $y);
+
+		if ($part === 'AB') {}
+    }
+
+}