diff --git a/src/Rules/Operators/InvalidIncDecOperationRule.php b/src/Rules/Operators/InvalidIncDecOperationRule.php
index 8c50854e7f..df766a668d 100644
--- a/src/Rules/Operators/InvalidIncDecOperationRule.php
+++ b/src/Rules/Operators/InvalidIncDecOperationRule.php
@@ -113,7 +113,7 @@ public function processNode(Node $node, Scope $scope): array
 			$deprecatedString = true;
 		}
 
-		$allowedTypes = [new FloatType(), new IntegerType(), $string, new ObjectType('SimpleXMLElement')];
+		$allowedTypes = [new FloatType(), new IntegerType(), $string, new ObjectType('SimpleXMLElement'), new ObjectType('GMP')];
 		$deprecatedNull = false;
 		if (
 			!$this->phpVersion->deprecatesDecOnNonNumericString()
diff --git a/tests/PHPStan/Rules/Operators/InvalidIncDecOperationRuleTest.php b/tests/PHPStan/Rules/Operators/InvalidIncDecOperationRuleTest.php
index 11e5981308..e7796e92f5 100644
--- a/tests/PHPStan/Rules/Operators/InvalidIncDecOperationRuleTest.php
+++ b/tests/PHPStan/Rules/Operators/InvalidIncDecOperationRuleTest.php
@@ -249,4 +249,9 @@ public function testBcMathNumber(): void
 		$this->analyse([__DIR__ . '/data/inc-dec-bcmath-number.php'], []);
 	}
 
+	public function testGmp(): void
+	{
+		$this->analyse([__DIR__ . '/data/inc-dec-gmp.php'], []);
+	}
+
 }
diff --git a/tests/PHPStan/Rules/Operators/data/inc-dec-gmp.php b/tests/PHPStan/Rules/Operators/data/inc-dec-gmp.php
new file mode 100644
index 0000000000..2cd5362142
--- /dev/null
+++ b/tests/PHPStan/Rules/Operators/data/inc-dec-gmp.php
@@ -0,0 +1,21 @@
+<?php
+
+namespace IncDecGmp;
+
+use GMP;
+
+function testPreInc(GMP $x): void {
+	++$x;
+}
+
+function testPostInc(GMP $x): void {
+	$x++;
+}
+
+function testPreDec(GMP $x): void {
+	--$x;
+}
+
+function testPostDec(GMP $x): void {
+	$x--;
+}