diff --git a/classes/controller.php b/classes/controller.php
index 9c4de280..9f4f4b56 100644
--- a/classes/controller.php
+++ b/classes/controller.php
@@ -21,6 +21,7 @@ use Grav\Common\Markdown\ParsedownExtra;
 use RocketTheme\Toolbox\Event\Event;
 use RocketTheme\Toolbox\File\File;
 use RocketTheme\Toolbox\File\JsonFile;
+use Symfony\Component\Yaml\Exception\ParseException;
 use Symfony\Component\Yaml\Yaml;
 
 class AdminController
@@ -1055,6 +1056,24 @@ class AdminController
         return $obj;
     }
 
+    public function checkValidFrontmatter($frontmatter)
+    {
+        try {
+            // Try native PECL YAML PHP extension first if available.
+            if (function_exists('yaml_parse')) {
+                $saved = @ini_get('yaml.decode_php');
+                @ini_set('yaml.decode_php', 0);
+                @yaml_parse("---\n" . $frontmatter . "\n...");
+                @ini_set('yaml.decode_php', $saved);
+            } else {
+                Yaml::parse($frontmatter);
+            }
+        } catch (ParseException $e) {
+            return false;
+        }
+        return true;
+    }
+
     /**
      * Handles form and saves the input data if its valid.
      *
@@ -1079,6 +1098,11 @@ class AdminController
             $route = !isset($data['route']) ? dirname($this->admin->route) : $data['route'];
             $obj = $this->admin->page(true);
 
+            if (isset($data['frontmatter']) && !$this->checkValidFrontmatter($data['frontmatter'])) {
+                $this->admin->setMessage($this->admin->translate('PLUGIN_ADMIN.INVALID_FRONTMATTER_COULD_NOT_SAVE'), 'error');
+                return false;
+            }
+
             //Handle system.home.hide_in_urls
             $hide_home_route = $config->get('system.home.hide_in_urls', false);
             if ($hide_home_route) {
diff --git a/languages/en.yaml b/languages/en.yaml
index 91646f93..5d76495b 100644
--- a/languages/en.yaml
+++ b/languages/en.yaml
@@ -474,3 +474,4 @@ PLUGIN_ADMIN:
   SESSION_HTTPONLY_HELP: "If true, indicates that cookies should be used only over HTTP, and JavaScript modification is not allowed"
   REVERSE_PROXY: "Reverse Proxy"
   REVERSE_PROXY_HELP: "Enable this if you are behind a reverse proxy and you are having trouble with URLs containing incorrect ports"
+  INVALID_FRONTMATTER_COULD_NOT_SAVE: "Invalid frontmatter, could not save"
\ No newline at end of file