diff --git a/build/baseline-8.0.neon b/build/baseline-8.0.neon
index 95dfa6cf8a..1618897e6e 100644
--- a/build/baseline-8.0.neon
+++ b/build/baseline-8.0.neon
@@ -29,8 +29,3 @@ parameters:
 			message: "#^Strict comparison using \\=\\=\\= between list<string> and false will always evaluate to false\\.$#"
 			count: 1
 			path: ../src/Type/Php/StrSplitFunctionReturnTypeExtension.php
-
-		-
-			message: "#^Call to function is_bool\\(\\) with string will always evaluate to false\\.$#"
-			count: 1
-			path: ../src/Type/Php/SubstrDynamicReturnTypeExtension.php
diff --git a/src/Type/Php/SubstrDynamicReturnTypeExtension.php b/src/Type/Php/SubstrDynamicReturnTypeExtension.php
index 00bfb3f33b..002340465b 100644
--- a/src/Type/Php/SubstrDynamicReturnTypeExtension.php
+++ b/src/Type/Php/SubstrDynamicReturnTypeExtension.php
@@ -24,6 +24,7 @@
 use function in_array;
 use function is_bool;
 use function mb_substr;
+use function strlen;
 use function substr;
 
 #[AutowiredService]
@@ -76,19 +77,29 @@ public function getTypeFromFunctionCall(
 				if ($length !== null) {
 					if ($functionReflection->getName() === 'mb_substr') {
 						$substr = mb_substr($constantString->getValue(), $offset->getValue(), $length->getValue());
+					} elseif ($this->phpVersion->substrReturnFalseInsteadOfEmptyString()) {
+						$substr = $this->substrOrFalse($constantString->getValue(), $offset->getValue(), $length->getValue());
 					} else {
 						$substr = substr($constantString->getValue(), $offset->getValue(), $length->getValue());
 					}
 				} else {
 					if ($functionReflection->getName() === 'mb_substr') {
 						$substr = mb_substr($constantString->getValue(), $offset->getValue());
+					} elseif ($this->phpVersion->substrReturnFalseInsteadOfEmptyString()) {
+						// Simulate substr call on an older PHP version if the runtime one is too new.
+						$substr = $this->substrOrFalse($constantString->getValue(), $offset->getValue());
 					} else {
 						$substr = substr($constantString->getValue(), $offset->getValue());
 					}
 				}
 
 				if (is_bool($substr)) {
-					$results[] = new ConstantBooleanType($substr);
+					if ($this->phpVersion->substrReturnFalseInsteadOfEmptyString()) {
+						$results[] = new ConstantBooleanType($substr);
+					} else {
+						// Simulate substr call on a recent PHP version if the runtime one is too old.
+						$results[] = new ConstantStringType('');
+					}
 				} else {
 					$results[] = new ConstantStringType($substr);
 				}
@@ -129,4 +140,28 @@ public function getTypeFromFunctionCall(
 		return null;
 	}
 
+	private function substrOrFalse(string $string, int $offset, ?int $length = null): false|string
+	{
+		$strlen = strlen($string);
+
+		if ($offset > $strlen) {
+			return false;
+		}
+
+		if ($length !== null && $length < 0) {
+			if ($offset < 0 && -$length > $strlen) {
+				return false;
+			}
+			if ($offset >= 0 && -$length > $strlen - $offset) {
+				return false;
+			}
+		}
+
+		if ($length === null) {
+			return substr($string, $offset);
+		}
+
+		return substr($string, $offset, $length);
+	}
+
 }
diff --git a/tests/PHPStan/Analyser/LooseConstComparisonPhp7Test.php b/tests/PHPStan/Analyser/LooseConstComparisonPhp7Test.php
index 582997ffa3..3b4f48d07a 100644
--- a/tests/PHPStan/Analyser/LooseConstComparisonPhp7Test.php
+++ b/tests/PHPStan/Analyser/LooseConstComparisonPhp7Test.php
@@ -34,7 +34,7 @@ public function testFileAsserts(
 	public static function getAdditionalConfigFiles(): array
 	{
 		return [
-			__DIR__ . '/looseConstComparisonPhp7.neon',
+			__DIR__ . '/nodeScopeResolverPhp7.neon',
 		];
 	}
 
diff --git a/tests/PHPStan/Analyser/LooseConstComparisonPhp8Test.php b/tests/PHPStan/Analyser/LooseConstComparisonPhp8Test.php
index 549a1d2de4..fae702cec2 100644
--- a/tests/PHPStan/Analyser/LooseConstComparisonPhp8Test.php
+++ b/tests/PHPStan/Analyser/LooseConstComparisonPhp8Test.php
@@ -34,7 +34,7 @@ public function testFileAsserts(
 	public static function getAdditionalConfigFiles(): array
 	{
 		return [
-			__DIR__ . '/looseConstComparisonPhp8.neon',
+			__DIR__ . '/nodeScopeResolverPhp8.neon',
 		];
 	}
 
diff --git a/tests/PHPStan/Analyser/SubstrPhp7Test.php b/tests/PHPStan/Analyser/SubstrPhp7Test.php
new file mode 100644
index 0000000000..561b33500c
--- /dev/null
+++ b/tests/PHPStan/Analyser/SubstrPhp7Test.php
@@ -0,0 +1,39 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Analyser;
+
+use PHPStan\Testing\TypeInferenceTestCase;
+use PHPUnit\Framework\Attributes\DataProvider;
+
+class SubstrPhp7Test extends TypeInferenceTestCase
+{
+
+	/**
+	 * @return iterable<array<string, mixed[]>>
+	 */
+	public static function dataFileAsserts(): iterable
+	{
+		yield from self::gatherAssertTypes(__DIR__ . '/data/bug-13129-php7.php');
+	}
+
+	/**
+	 * @param mixed ...$args
+	 */
+	#[DataProvider('dataFileAsserts')]
+	public function testFileAsserts(
+		string $assertType,
+		string $file,
+		...$args,
+	): void
+	{
+		$this->assertFileAsserts($assertType, $file, ...$args);
+	}
+
+	public static function getAdditionalConfigFiles(): array
+	{
+		return [
+			__DIR__ . '/nodeScopeResolverPhp7.neon',
+		];
+	}
+
+}
diff --git a/tests/PHPStan/Analyser/SubstrPhp8Test.php b/tests/PHPStan/Analyser/SubstrPhp8Test.php
new file mode 100644
index 0000000000..934a7ac78c
--- /dev/null
+++ b/tests/PHPStan/Analyser/SubstrPhp8Test.php
@@ -0,0 +1,39 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Analyser;
+
+use PHPStan\Testing\TypeInferenceTestCase;
+use PHPUnit\Framework\Attributes\DataProvider;
+
+class SubstrPhp8Test extends TypeInferenceTestCase
+{
+
+	/**
+	 * @return iterable<array<string, mixed[]>>
+	 */
+	public static function dataFileAsserts(): iterable
+	{
+		yield from self::gatherAssertTypes(__DIR__ . '/data/bug-13129-php8.php');
+	}
+
+	/**
+	 * @param mixed ...$args
+	 */
+	#[DataProvider('dataFileAsserts')]
+	public function testFileAsserts(
+		string $assertType,
+		string $file,
+		...$args,
+	): void
+	{
+		$this->assertFileAsserts($assertType, $file, ...$args);
+	}
+
+	public static function getAdditionalConfigFiles(): array
+	{
+		return [
+			__DIR__ . '/nodeScopeResolverPhp8.neon',
+		];
+	}
+
+}
diff --git a/tests/PHPStan/Analyser/data/bug-13129-php7.php b/tests/PHPStan/Analyser/data/bug-13129-php7.php
new file mode 100644
index 0000000000..c12e1db1a6
--- /dev/null
+++ b/tests/PHPStan/Analyser/data/bug-13129-php7.php
@@ -0,0 +1,9 @@
+<?php
+
+namespace Bug13129PHP7;
+
+use function PHPStan\Testing\assertType;
+
+assertType("false", substr("test", 5));
+assertType("false", substr("test", -1, -5));
+assertType("false", substr("test", 1, -4));
diff --git a/tests/PHPStan/Analyser/data/bug-13129-php8.php b/tests/PHPStan/Analyser/data/bug-13129-php8.php
new file mode 100644
index 0000000000..62531c8a47
--- /dev/null
+++ b/tests/PHPStan/Analyser/data/bug-13129-php8.php
@@ -0,0 +1,9 @@
+<?php
+
+namespace Bug13129PHP8;
+
+use function PHPStan\Testing\assertType;
+
+assertType("''", substr("test", 5));
+assertType("''", substr("test", -1, -5));
+assertType("''", substr("test", 1, -4));
diff --git a/tests/PHPStan/Analyser/looseConstComparisonPhp7.neon b/tests/PHPStan/Analyser/nodeScopeResolverPhp7.neon
similarity index 100%
rename from tests/PHPStan/Analyser/looseConstComparisonPhp7.neon
rename to tests/PHPStan/Analyser/nodeScopeResolverPhp7.neon
diff --git a/tests/PHPStan/Analyser/looseConstComparisonPhp8.neon b/tests/PHPStan/Analyser/nodeScopeResolverPhp8.neon
similarity index 100%
rename from tests/PHPStan/Analyser/looseConstComparisonPhp8.neon
rename to tests/PHPStan/Analyser/nodeScopeResolverPhp8.neon