diff --git a/ChangeLog b/ChangeLog
index 7f9768d41a..e2a7d3b39b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -27,6 +27,7 @@ phpMyAdmin - ChangeLog
 - bug #3984 Cannot insert in this table (PHP < 5.4)
 - bug #3989 Reloading privileges does not update the interface
 - bug #3960 NavigationBarIconic config not honored
+- bug #3985 Call to undefined function mb_detect_encoding
 
 4.0.4.0 (2013-06-17)
 - bug #3959 Using DefaultTabDatabase in NavigationTree for Database Click
diff --git a/libraries/common.inc.php b/libraries/common.inc.php
index 2b52b69e46..78fc012810 100644
--- a/libraries/common.inc.php
+++ b/libraries/common.inc.php
@@ -94,6 +94,13 @@ require './libraries/core.lib.php';
  */
 require './libraries/sanitizing.lib.php';
 
+/**
+ * Warning about mbstring.
+ */
+if (! function_exists('mb_detect_encoding')) {
+    PMA_warnMissingExtension('mbstring', $fatal = true);
+}
+
 /**
  * the PMA_Theme class
  */