diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 4e8cc27..60d4f7a 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -60,3 +60,18 @@ jobs:
         run: |
           wget https://scrutinizer-ci.com/ocular.phar
           php ocular.phar code-coverage:upload --format=php-clover build/coverage.xml
+
+  phpstan:
+    name: PHPStan
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v3
+
+      - name: PHPStan
+        uses: OskarStark/phpstan-ga@0.12.32
+        env:
+          REQUIRE_DEV: false
+        with:
+          args: analyze --no-progress
diff --git a/CHANGELOG.md b/CHANGELOG.md
index b57b33b..fafc207 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,11 @@
 # Change Log
 
+## 1.2.1
+
+### Added
+
+- Fixed PHPDoc for `wait()` and `then()`'s `onRejected` callable
+
 ## 1.2.0 - 2023-10-24
 
 ### Added
diff --git a/phpstan.neon.dist b/phpstan.neon.dist
new file mode 100644
index 0000000..f8b94cf
--- /dev/null
+++ b/phpstan.neon.dist
@@ -0,0 +1,6 @@
+parameters:
+    level: max
+    checkMissingIterableValueType: false
+    treatPhpDocTypesAsCertain: false
+    paths:
+        - src
diff --git a/src/FulfilledPromise.php b/src/FulfilledPromise.php
index dce0431..c9158e7 100644
--- a/src/FulfilledPromise.php
+++ b/src/FulfilledPromise.php
@@ -58,5 +58,7 @@ public function wait($unwrap = true)
         if ($unwrap) {
             return $this->result;
         }
+
+        return;
     }
 }
diff --git a/src/Promise.php b/src/Promise.php
index 9383726..81434ae 100644
--- a/src/Promise.php
+++ b/src/Promise.php
@@ -39,7 +39,7 @@ interface Promise
      * The callback will be called when the value arrived and never more than once.
      *
      * @param callable(T): V|null          $onFulfilled called when a response will be available
-     * @param callable(\Exception): V|null $onRejected  called when an exception occurs
+     * @param callable(\Throwable): V|null $onRejected  called when an exception occurs
      *
      * @return Promise<V> a new resolved promise with value of the executed callback (onFulfilled / onRejected)
      *
@@ -65,7 +65,7 @@ public function getState();
      *
      * @param bool $unwrap Whether to return resolved value / throw reason or not
      *
-     * @return T Resolved value, null if $unwrap is set to false
+     * @return ($unwrap is true ? T : null) Resolved value, null if $unwrap is set to false
      *
      * @throws \Exception the rejection reason if $unwrap is set to true and the request failed
      */
diff --git a/src/RejectedPromise.php b/src/RejectedPromise.php
index 2cbefec..a500048 100644
--- a/src/RejectedPromise.php
+++ b/src/RejectedPromise.php
@@ -55,5 +55,7 @@ public function wait($unwrap = true)
         if ($unwrap) {
             throw $this->exception;
         }
+
+        return;
     }
 }