diff --git a/lib/classes/output/icon_system_fontawesome.php b/lib/classes/output/icon_system_fontawesome.php
index c9dca916837..dcd18da1220 100644
--- a/lib/classes/output/icon_system_fontawesome.php
+++ b/lib/classes/output/icon_system_fontawesome.php
@@ -434,7 +434,10 @@ class icon_system_fontawesome extends icon_system_font {
         if ($this->map === []) {
             $cache = \cache::make('core', 'fontawesomeiconmapping');
 
-            $this->map = $cache->get('mapping');
+            // Create different mapping keys for different icon system classes, there may be several different
+            // themes on the same site.
+            $mapkey = 'mapping_'.preg_replace('/[^a-zA-Z0-9_]/', '_', get_class($this));
+            $this->map = $cache->get($mapkey);
 
             if (empty($this->map)) {
                 $this->map = $this->get_core_icon_map();
@@ -448,7 +451,7 @@ class icon_system_fontawesome extends icon_system_font {
                         }
                     }
                 }
-                $cache->set('mapping', $this->map);
+                $cache->set($mapkey, $this->map);
             }
 
         }