diff --git a/rtl/win16/system.pp b/rtl/win16/system.pp
index 5aa8309f84..72763a5f49 100644
--- a/rtl/win16/system.pp
+++ b/rtl/win16/system.pp
@@ -3,6 +3,7 @@ unit system;
 interface
 
 {$DEFINE FPC_NO_DEFAULT_HEAP}
+{$DEFINE FPC_NO_DEFAULT_MEMORYMANAGER}
 {$DEFINE HAS_MEMORYMANAGER}
 
 {$DEFINE FPC_INCLUDE_SOFTWARE_MUL}