diff --git a/core/modules/system/system.install b/core/modules/system/system.install
index 97f726f..a46f967 100644
--- a/core/modules/system/system.install
+++ b/core/modules/system/system.install
@@ -1464,6 +1464,7 @@ function system_update_8005() {
         break;
 
       case 'classy':
+      case 'stable':
         // Don't place any blocks or trigger custom themes installed warning.
         break;
 
@@ -1541,6 +1542,7 @@ function system_update_8006() {
 
       case 'seven':
       case 'classy':
+      case 'stable':
         // Don't place any blocks or trigger custom themes installed warning.
         break;
       default: