diff --git a/src/Reflection/FunctionReflection.php b/src/Reflection/FunctionReflection.php
index fabddd04fa..e7b12f316e 100644
--- a/src/Reflection/FunctionReflection.php
+++ b/src/Reflection/FunctionReflection.php
@@ -99,6 +99,16 @@ public function getParameters(): array
 					true
 				);
 			}
+			if (
+				$this->reflection->getName() === 'unpack'
+				&& PHP_VERSION_ID >= 70101
+			) {
+				$this->parameters[2] = new DummyParameter(
+					'offset',
+					new IntegerType(false),
+					true
+				);
+			}
 		}
 
 		return $this->parameters;
diff --git a/tests/PHPStan/Rules/Functions/CallToFunctionParametersRuleTest.php b/tests/PHPStan/Rules/Functions/CallToFunctionParametersRuleTest.php
index 8902f444a6..19a30d1f78 100644
--- a/tests/PHPStan/Rules/Functions/CallToFunctionParametersRuleTest.php
+++ b/tests/PHPStan/Rules/Functions/CallToFunctionParametersRuleTest.php
@@ -104,4 +104,34 @@ public function testCallToWeirdFunctions()
 		]);
 	}
 
+	/**
+	 * @requires PHP 7.1.1
+	 */
+	public function testUnpackOnAfter711()
+	{
+		$this->analyse([__DIR__ . '/data/unpack.php'], [
+			[
+				'Function unpack invoked with 0 parameters, 2-3 required.',
+				3,
+			],
+		]);
+	}
+
+	public function testUnpackOnBefore711()
+	{
+		if (PHP_VERSION_ID >= 70101) {
+			$this->markTestSkipped('This test requires PHP < 7.1.1');
+		}
+		$this->analyse([__DIR__ . '/data/unpack.php'], [
+			[
+				'Function unpack invoked with 0 parameters, 2 required.',
+				3,
+			],
+			[
+				'Function unpack invoked with 3 parameters, 2 required.',
+				4,
+			],
+		]);
+	}
+
 }
diff --git a/tests/PHPStan/Rules/Functions/data/unpack.php b/tests/PHPStan/Rules/Functions/data/unpack.php
new file mode 100644
index 0000000000..f5ac4f0e1b
--- /dev/null
+++ b/tests/PHPStan/Rules/Functions/data/unpack.php
@@ -0,0 +1,4 @@
+<?php
+
+unpack();
+unpack($format, $data, 1);