diff --git a/src/Redmine/Api/AbstractApi.php b/src/Redmine/Api/AbstractApi.php
index 9aa1a0f1..93033245 100644
--- a/src/Redmine/Api/AbstractApi.php
+++ b/src/Redmine/Api/AbstractApi.php
@@ -42,7 +42,7 @@ public function lastCallFailed()
      * @param string $path
      * @param bool   $decodeIfJson
      *
-     * @return string|array|SimpleXMLElement|null
+     * @return string|array|SimpleXMLElement|false
      */
     protected function get($path, $decodeIfJson = true)
     {
@@ -64,7 +64,7 @@ protected function get($path, $decodeIfJson = true)
             }
         }
 
-        return ('' === $body) ? null : $body;
+        return ('' === $body) ? false : $body;
     }
 
     /**
diff --git a/src/Redmine/Api/IssueRelation.php b/src/Redmine/Api/IssueRelation.php
index a0fc1d15..bb6aa31f 100644
--- a/src/Redmine/Api/IssueRelation.php
+++ b/src/Redmine/Api/IssueRelation.php
@@ -42,7 +42,7 @@ public function all($issueId, array $params = [])
     public function show($id)
     {
         $ret = $this->get('/relations/'.urlencode($id).'.json');
-        if (null === $ret) {
+        if (false === $ret) {
             return [];
         }
 
diff --git a/tests/Unit/Api/AbstractApiTest.php b/tests/Unit/Api/AbstractApiTest.php
index d377f994..971e7b36 100644
--- a/tests/Unit/Api/AbstractApiTest.php
+++ b/tests/Unit/Api/AbstractApiTest.php
@@ -129,7 +129,8 @@ public function getJsonDecodingFromGetMethodData()
             ['{"foo_bar": 12345}', null, ['foo_bar' => 12345]], // test decode by default
             ['{"foo_bar": 12345}', false, '{"foo_bar": 12345}'],
             ['{"foo_bar": 12345}', true, ['foo_bar' => 12345]],
-            ['', true, null], // test decode with empty body
+            'Empty body, JSON decode: false' => ['', false, false],
+            'Empty body, JSON decode: true' => ['', true, false],
             ['{"foo_bar":', true, 'Error decoding body as JSON: Syntax error'], // test invalid JSON
         ];
     }