diff --git a/src/CredentialsLoader.php b/src/CredentialsLoader.php
index d5d59b6be..b71ee9044 100644
--- a/src/CredentialsLoader.php
+++ b/src/CredentialsLoader.php
@@ -80,10 +80,16 @@ public static function fromEnv()
         if (empty($path)) {
             return null;
         }
+
+        if (is_string($path) && str_starts_with($path, '{')) {
+            return json_decode($path, true);
+        }
+
         if (!file_exists($path)) {
             $cause = 'file ' . $path . ' does not exist';
             throw new \DomainException(self::unableToReadEnv($cause));
         }
+
         $jsonKey = file_get_contents($path);
 
         return json_decode((string) $jsonKey, true);
diff --git a/tests/ApplicationDefaultCredentialsTest.php b/tests/ApplicationDefaultCredentialsTest.php
index 1db9b9e43..6a5b84bba 100644
--- a/tests/ApplicationDefaultCredentialsTest.php
+++ b/tests/ApplicationDefaultCredentialsTest.php
@@ -68,6 +68,16 @@ public function testLoadsOKIfEnvSpecifiedIsValid()
         );
     }
 
+    public function testLoadsOKIfEnvSpecifiedIsAJsonString()
+    {
+        $json = file_get_contents(__DIR__ . '/fixtures' . '/private.json');
+
+        putenv(ServiceAccountCredentials::ENV_VAR . '=' . $json);
+        $this->assertNotNull(
+            ApplicationDefaultCredentials::getCredentials('a scope')
+        );
+    }
+
     public function testLoadsDefaultFileIfPresentAndEnvVarIsNotSet()
     {
         putenv('HOME=' . __DIR__ . '/fixtures');