diff --git a/libraries/common.inc.php b/libraries/common.inc.php
index bd734a57cf..2b52b69e46 100644
--- a/libraries/common.inc.php
+++ b/libraries/common.inc.php
@@ -284,6 +284,13 @@ if (! function_exists('preg_replace')) {
     PMA_warnMissingExtension('pcre', true);
 }
 
+/**
+ * JSON is required in several places.
+ */
+if (! function_exists('json_encode')) {
+    PMA_warnMissingExtension('json', true);
+}
+
 /**
  * @global PMA_Config $GLOBALS['PMA_Config']
  * force reading of config file, because we removed sensitive values