diff --git a/src/classes/site.ts b/src/classes/site.ts
index e7776a33c..845a9496f 100644
--- a/src/classes/site.ts
+++ b/src/classes/site.ts
@@ -212,7 +212,7 @@ export class CoreSite {
         3.6: 2018120300,
         3.7: 2019052000
     };
-    static MINIMUM_MOODLE_VERSION = 3.1;
+    static MINIMUM_MOODLE_VERSION = '3.1';
 
     // Possible cache update frequencies.
     protected UPDATE_FREQUENCIES = [