diff --git a/project.xml b/project.xml
index bae993c..d1dcb86 100644
--- a/project.xml
+++ b/project.xml
@@ -10,7 +10,7 @@
   </build>
 
   <modules>
-    <module>rtl</module>
+    <module activeByDefault="false">rtl</module>
     <module>compiler</module>
     <module>tools/migration-analyser</module>
   </modules>
diff --git a/rtl/project.xml b/rtl/project.xml
index 8c49d51..70960b0 100644
--- a/rtl/project.xml
+++ b/rtl/project.xml
@@ -6,6 +6,10 @@
   <build>
     <packaging>library</packaging>
     <!-- mainSource not needed — PasBuild auto-generates bootstrap -->
+    <!-- System.pas is compiled by Blaise, not FPC; FPC already provides System implicitly -->
+    <bootstrapExclude>
+      <unit>System</unit>
+    </bootstrapExclude>
   </build>
 
   <test>