diff --git a/phpstan-baseline.neon b/phpstan-baseline.neon
new file mode 100644
index 0000000..cf32830
--- /dev/null
+++ b/phpstan-baseline.neon
@@ -0,0 +1,13 @@
+parameters:
+	ignoreErrors:
+		-
+			message: '#^Method Http\\Promise\\FulfilledPromise\:\:then\(\) should return Http\\Promise\\Promise\<V\> but returns Http\\Promise\\RejectedPromise\<mixed\>\.$#'
+			identifier: return.type
+			count: 1
+			path: src/FulfilledPromise.php
+
+		-
+			message: '#^Method Http\\Promise\\RejectedPromise\:\:then\(\) should return Http\\Promise\\Promise\<V\> but returns Http\\Promise\\RejectedPromise\<mixed\>\.$#'
+			identifier: return.type
+			count: 1
+			path: src/RejectedPromise.php
diff --git a/phpstan.neon.dist b/phpstan.neon.dist
index f8b94cf..66aff41 100644
--- a/phpstan.neon.dist
+++ b/phpstan.neon.dist
@@ -1,6 +1,7 @@
 parameters:
     level: max
-    checkMissingIterableValueType: false
     treatPhpDocTypesAsCertain: false
     paths:
         - src
+includes:
+    - phpstan-baseline.neon