diff --git a/composer.json b/composer.json
index b813b77e91c..47d19647686 100644
--- a/composer.json
+++ b/composer.json
@@ -24,7 +24,7 @@
         "ext-imagick": "*",
         "ext-mcrypt": "*",
         "ext-openssl": "*",
-        "ext-mb_string": "*",
+        "ext-mbstring": "*",
         "ext-soap": "*"
     }
 }