diff --git a/CHANGELOG.md b/CHANGELOG.md
index 942539a..c50d9f3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## NOT RELEASED
 
+### Changed
+
+- Add `Accept: application/json` header in request to fix incompatibility with 3rd party providers
+
 ## 1.1.1
 
 ### Changed
diff --git a/src/Input/GetThingShadowRequest.php b/src/Input/GetThingShadowRequest.php
index 3e8a59f..d0f2871 100644
--- a/src/Input/GetThingShadowRequest.php
+++ b/src/Input/GetThingShadowRequest.php
@@ -70,7 +70,10 @@ public function getThingName(): ?string
     public function request(): Request
     {
         // Prepare headers
-        $headers = ['content-type' => 'application/json'];
+        $headers = [
+            'Content-Type' => 'application/json',
+            'Accept' => 'application/json',
+        ];
 
         // Prepare query
         $query = [];
diff --git a/src/Input/UpdateThingShadowRequest.php b/src/Input/UpdateThingShadowRequest.php
index 4ed7bfb..1886bfe 100644
--- a/src/Input/UpdateThingShadowRequest.php
+++ b/src/Input/UpdateThingShadowRequest.php
@@ -87,7 +87,10 @@ public function getThingName(): ?string
     public function request(): Request
     {
         // Prepare headers
-        $headers = ['content-type' => 'application/json'];
+        $headers = [
+            'Content-Type' => 'application/json',
+            'Accept' => 'application/json',
+        ];
 
         // Prepare query
         $query = [];
diff --git a/tests/Unit/Input/GetThingShadowRequestTest.php b/tests/Unit/Input/GetThingShadowRequestTest.php
index 1620918..aa93c99 100644
--- a/tests/Unit/Input/GetThingShadowRequestTest.php
+++ b/tests/Unit/Input/GetThingShadowRequestTest.php
@@ -17,7 +17,8 @@ public function testRequest(): void
         // see https://docs.aws.amazon.com/iot/latest/apireference/API_Operations_AWS_IoT_Data_Plane.html/API_GetThingShadow.html
         $expected = '
             GET /things/unit21_hvac/shadow?name=temperature HTTP/1.0
-            Content-Type: application/json
+            Content-type: application/json
+            Accept: application/json
         ';
 
         self::assertRequestEqualsHttpRequest($expected, $input->request());
diff --git a/tests/Unit/Input/UpdateThingShadowRequestTest.php b/tests/Unit/Input/UpdateThingShadowRequestTest.php
index a9e3c65..2ae2746 100644
--- a/tests/Unit/Input/UpdateThingShadowRequestTest.php
+++ b/tests/Unit/Input/UpdateThingShadowRequestTest.php
@@ -18,7 +18,8 @@ public function testRequest(): void
         // see https://docs.aws.amazon.com/iot/latest/apireference/API_Operations_AWS_IoT_Data_Plane.html/API_UpdateThingShadow.html
         $expected = '
             POST /things/unit21_hvac/shadow?name=temperature HTTP/1.0
-            Content-Type: application/json
+            Content-type: application/json
+            Accept: application/json
 
             {
                 "state": {