diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 6c15006..7222968 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -13,7 +13,7 @@ jobs:
 
     strategy:
       matrix:
-        php: ['7.3', '7.4', '8.0']
+        php: ['8.0','8.1']
 
     steps:
       - name: "Checkout"
@@ -44,7 +44,7 @@ jobs:
 
     strategy:
       matrix:
-        php: ['7.3', '7.4', '8.0']
+        php: ['8.0','8.1']
 
     steps:
       - name: "Checkout"
diff --git a/Makefile b/Makefile
index 022c819..a0cee93 100644
--- a/Makefile
+++ b/Makefile
@@ -11,16 +11,16 @@ test:
 	$(MAKE) fmt-check
 
 phpstan:
-	docker run -it --rm -v ${PWD}:/app -w /app php:7.3-cli-alpine php -d error_reporting=-1 -d memory_limit=-1 bin/phpstan --ansi analyse
+	docker run -it --rm -v ${PWD}:/app -w /app php:8.3-cli-alpine php -d error_reporting=-1 -d memory_limit=-1 bin/phpstan --ansi analyse
 
 phpstan-clear-cache:
-	docker run -it --rm -v ${PWD}:/app -w /app php:7.3-cli-alpine php -d error_reporting=-1 -d memory_limit=-1 bin/phpstan --ansi clear-result-cache
+	docker run -it --rm -v ${PWD}:/app -w /app php:8.3-cli-alpine php -d error_reporting=-1 -d memory_limit=-1 bin/phpstan --ansi clear-result-cache
 
 phpunit:
-	docker run -it --rm -v ${PWD}:/app -w /app php:7.3-cli-alpine php -d error_reporting=-1 bin/phpunit --colors=always -c phpunit.xml
+	docker run -it --rm -v ${PWD}:/app -w /app php:8.3-cli-alpine php -d error_reporting=-1 bin/phpunit --colors=always -c phpunit.xml
 
 fmt-check:
-	docker run -it --rm -v ${PWD}:/app -w /app php:7.3-cli-alpine php bin/phpcs --standard=./ruleset.xml --extensions=php --tab-width=4 -sp ./src ./tests
+	docker run -it --rm -v ${PWD}:/app -w /app php:8.3-cli-alpine php bin/phpcs --standard=./ruleset.xml --extensions=php --tab-width=4 -sp ./src ./tests
 
 fmt:
-	docker run -it --rm -v ${PWD}:/app -w /app php:7.3-cli-alpine php bin/phpcbf --standard=./ruleset.xml --extensions=php --tab-width=4 -sp ./src ./tests
+	docker run -it --rm -v ${PWD}:/app -w /app php:8.3-cli-alpine php bin/phpcbf --standard=./ruleset.xml --extensions=php --tab-width=4 -sp ./src ./tests
diff --git a/composer.json b/composer.json
index ed9a136..222d15b 100644
--- a/composer.json
+++ b/composer.json
@@ -10,8 +10,8 @@
     }
   ],
   "require": {
-    "php": ">=7.3|^8.0",
-    "phpstan/phpstan": "^1.0"
+    "php": ">=7.4|^8.0",
+    "phpstan/phpstan": "^2.0"
   },
   "require-dev": {
     "roave/security-advisories": "dev-latest",
@@ -19,7 +19,7 @@
     "phpunit/phpunit": "^9.4.2",
     "slevomat/coding-standard": "^6.4.1",
     "squizlabs/php_codesniffer": "^3.5.0",
-    "bonami/collections": "^0.4.5"
+    "bonami/collections": "dev-upgrade-to-phpstan2"
   },
   "config": {
     "bin-dir": "bin",
diff --git a/phpstan.neon b/phpstan.neon
index 90931bc..82eb315 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -2,6 +2,10 @@ includes:
     - extension.neon
     - vendor/phpstan/phpstan/conf/bleedingEdge.neon
 parameters:
+    ignoreErrors:
+        -
+            identifier: phpstanApi.instanceofType
+        - '~Method .* should return class-string but returns string.~'
     reportUnmatchedIgnoredErrors: true
     level: 9
     paths:
diff --git a/src/Bonami/Collection/Phpstan/GroupByMethodReturnTypeExtension.php b/src/Bonami/Collection/Phpstan/GroupByMethodReturnTypeExtension.php
index 913e840..017713f 100644
--- a/src/Bonami/Collection/Phpstan/GroupByMethodReturnTypeExtension.php
+++ b/src/Bonami/Collection/Phpstan/GroupByMethodReturnTypeExtension.php
@@ -43,8 +43,9 @@ public function getTypeFromMethodCall(
     ): Type {
         $arg = $methodCall->args[0];
         assert($arg instanceof Arg);
+
         $closure = $scope->getType($arg->value);
-        assert($closure instanceof ClosureType || $closure instanceof CallableType);
+        assert($closure instanceof ClosureType);
 
         $listType = $scope->getType($methodCall->var);
 
diff --git a/tests/Bonami/Collection/Phpstan/MapTest.php b/tests/Bonami/Collection/Phpstan/MapTest.php
index 04a8222..06b77d4 100644
--- a/tests/Bonami/Collection/Phpstan/MapTest.php
+++ b/tests/Bonami/Collection/Phpstan/MapTest.php
@@ -12,6 +12,7 @@ class MapTest extends TestCase
     public function testFromAssociativeArrayReturnType(): void
     {
         $genericList = Map::fromAssociativeArray([1 => new Foo()]);
+        // @phpstan-ignore-next-line
         $this->requireMapOfFoo($genericList);
         self::assertInstanceOf(Map::class, $genericList);