diff --git a/src/Curl/Curl.php b/src/Curl/Curl.php
index 9ef9fd6..037da9d 100644
--- a/src/Curl/Curl.php
+++ b/src/Curl/Curl.php
@@ -2155,7 +2155,8 @@ class Curl
             }
         }
 
-        if (isset($response_headers['Content-Encoding']) && $response_headers['Content-Encoding'] === 'gzip') {
+        if (isset($response_headers['Content-Encoding']) && $response_headers['Content-Encoding'] === 'gzip' &&
+            is_string($response)) {
             // Use @ to suppress message "Warning gzdecode(): data error".
             $decoded_response = @gzdecode($response);
             if ($decoded_response !== false) {
diff --git a/tests/PHPCurlClass/PHPCurlClassTest.php b/tests/PHPCurlClass/PHPCurlClassTest.php
index 3622f61..e07708c 100644
--- a/tests/PHPCurlClass/PHPCurlClassTest.php
+++ b/tests/PHPCurlClass/PHPCurlClassTest.php
@@ -4411,4 +4411,25 @@ class CurlTest extends \PHPUnit\Framework\TestCase
         $this->assertEquals('gzip', $test->curl->responseHeaders['content-encoding']);
         $this->assertEquals('<html><body>not gzip-encoded</body></html>', $test->curl->response);
     }
+
+    public function testGzipDecodingNonStringResponseWithoutError()
+    {
+        $test = new Test();
+        $test->curl->setDefaultDecoder(function () {
+            $response = new \stdClass();
+            $response->{'abc'} = 'foo';
+            $response->{'123'} = 'bar';
+            return $response;
+        });
+        $test->server('json_response', 'POST', [
+            'headers' => [
+                'content-type: text/html; charset=utf-8',
+                'content-encoding: gzip',
+            ],
+        ]);
+        $this->assertEquals('text/html; charset=utf-8', $test->curl->responseHeaders['content-type']);
+        $this->assertEquals('gzip', $test->curl->responseHeaders['content-encoding']);
+        $this->assertEquals('foo', $test->curl->response->{'abc'});
+        $this->assertEquals('bar', $test->curl->response->{'123'});
+    }
 }