diff --git a/lib/classes/plugin_manager.php b/lib/classes/plugin_manager.php
index f0d7455e592..7ae4380e5ff 100644
--- a/lib/classes/plugin_manager.php
+++ b/lib/classes/plugin_manager.php
@@ -662,6 +662,10 @@ class core_plugin_manager {
             return 'svn';
         }
 
+        if (is_dir($pluginroot.'/.hg')) {
+            return 'mercurial';
+        }
+
         return false;
     }
 
diff --git a/lib/classes/update/deployer.php b/lib/classes/update/deployer.php
index 0eccb8e9e7d..d25560920e4 100644
--- a/lib/classes/update/deployer.php
+++ b/lib/classes/update/deployer.php
@@ -189,6 +189,10 @@ class deployer {
             return 'svn';
         }
 
+        if (is_dir($pluginroot.'/.hg')) {
+            return 'mercurial';
+        }
+
         return false;
     }