diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2576e0eb1..a727c20a3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,7 @@
 
 1. [](#new)
     * Added `Uri::method()` to get current HTTP method (GET/POST etc)
+    * Added `FormatterInterface::getSupportedFileExtensions()` method, deprecated `getFileExtension()`
 
 # v1.5.0-rc.1
 ## 07/31/2018
diff --git a/system/src/Grav/Framework/File/Formatter/FormatterInterface.php b/system/src/Grav/Framework/File/Formatter/FormatterInterface.php
index 84af00b63..35ceccfde 100644
--- a/system/src/Grav/Framework/File/Formatter/FormatterInterface.php
+++ b/system/src/Grav/Framework/File/Formatter/FormatterInterface.php
@@ -11,11 +11,11 @@ namespace Grav\Framework\File\Formatter;
 interface FormatterInterface
 {
     /**
-     * Get file extension with dot.
+     * Get file extensions supported by current formatter (with dot).
      *
-     * @return string
+     * @return string[]
      */
-    public function getFileExtension();
+    public function getSupportedFileExtensions();
 
     /**
      * Encode data into a string.
diff --git a/system/src/Grav/Framework/File/Formatter/IniFormatter.php b/system/src/Grav/Framework/File/Formatter/IniFormatter.php
index e7ad2833c..15d67c4e2 100644
--- a/system/src/Grav/Framework/File/Formatter/IniFormatter.php
+++ b/system/src/Grav/Framework/File/Formatter/IniFormatter.php
@@ -25,11 +25,20 @@ class IniFormatter implements FormatterInterface
     }
 
     /**
-     * {@inheritdoc}
+     * @deprecated
+     * @internal
      */
     public function getFileExtension()
     {
-        return $this->config['file_extension'];
+        return $this->getSupportedFileExtensions()[0];
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getSupportedFileExtensions()
+    {
+        return (array) $this->config['file_extension'];
     }
 
     /**
diff --git a/system/src/Grav/Framework/File/Formatter/JsonFormatter.php b/system/src/Grav/Framework/File/Formatter/JsonFormatter.php
index 12c245016..bd01b8307 100644
--- a/system/src/Grav/Framework/File/Formatter/JsonFormatter.php
+++ b/system/src/Grav/Framework/File/Formatter/JsonFormatter.php
@@ -23,11 +23,20 @@ class JsonFormatter implements FormatterInterface
     }
 
     /**
-     * {@inheritdoc}
+     * @deprecated
+     * @internal
      */
     public function getFileExtension()
     {
-        return $this->config['file_extension'];
+        return $this->getSupportedFileExtensions()[0];
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getSupportedFileExtensions()
+    {
+        return (array) $this->config['file_extension'];
     }
 
     /**
diff --git a/system/src/Grav/Framework/File/Formatter/MarkdownFormatter.php b/system/src/Grav/Framework/File/Formatter/MarkdownFormatter.php
index 7269c2fe7..c38f691f1 100644
--- a/system/src/Grav/Framework/File/Formatter/MarkdownFormatter.php
+++ b/system/src/Grav/Framework/File/Formatter/MarkdownFormatter.php
@@ -29,11 +29,20 @@ class MarkdownFormatter implements FormatterInterface
     }
 
     /**
-     * {@inheritdoc}
+     * @deprecated
+     * @internal
      */
     public function getFileExtension()
     {
-        return $this->config['file_extension'];
+        return $this->getSupportedFileExtensions()[0];
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getSupportedFileExtensions()
+    {
+        return (array) $this->config['file_extension'];
     }
 
     /**
diff --git a/system/src/Grav/Framework/File/Formatter/SerializeFormatter.php b/system/src/Grav/Framework/File/Formatter/SerializeFormatter.php
index 3c581efa5..95744104c 100644
--- a/system/src/Grav/Framework/File/Formatter/SerializeFormatter.php
+++ b/system/src/Grav/Framework/File/Formatter/SerializeFormatter.php
@@ -25,11 +25,20 @@ class SerializeFormatter implements FormatterInterface
     }
 
     /**
-     * {@inheritdoc}
+     * @deprecated
+     * @internal
      */
     public function getFileExtension()
     {
-        return $this->config['file_extension'];
+        return $this->getSupportedFileExtensions()[0];
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getSupportedFileExtensions()
+    {
+        return (array) $this->config['file_extension'];
     }
 
     /**
diff --git a/system/src/Grav/Framework/File/Formatter/YamlFormatter.php b/system/src/Grav/Framework/File/Formatter/YamlFormatter.php
index 9a5d60278..ee18061ea 100644
--- a/system/src/Grav/Framework/File/Formatter/YamlFormatter.php
+++ b/system/src/Grav/Framework/File/Formatter/YamlFormatter.php
@@ -30,11 +30,20 @@ class YamlFormatter implements FormatterInterface
     }
 
     /**
-     * {@inheritdoc}
+     * @deprecated
+     * @internal
      */
     public function getFileExtension()
     {
-        return $this->config['file_extension'];
+        return $this->getSupportedFileExtensions()[0];
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getSupportedFileExtensions()
+    {
+        return (array) $this->config['file_extension'];
     }
 
     /**