diff --git a/src/system/libroot/os/arch/x86/Jamfile b/src/system/libroot/os/arch/x86/Jamfile
index 7c5fdb3bb9..d84bf002cc 100644
--- a/src/system/libroot/os/arch/x86/Jamfile
+++ b/src/system/libroot/os/arch/x86/Jamfile
@@ -3,6 +3,7 @@ SubDir OBOS_TOP src system libroot os arch x86 ;
 KernelMergeObject os_arch_$(OBOS_ARCH).o :
 	atomic.S
 	byteorder.S
+	compatibility.c
 	get_stack_frame.S
 	system_info.c
 	system_time.S
diff --git a/src/system/libroot/os/arch/x86/compatibility.c b/src/system/libroot/os/arch/x86/compatibility.c
new file mode 100644
index 0000000000..493c58402c
--- /dev/null
+++ b/src/system/libroot/os/arch/x86/compatibility.c
@@ -0,0 +1,27 @@
+/*
+ * Copyright 2005, Axel Dörfler, axeld@pinc-software.de. All rights reserved.
+ * Distributed under the terms of the MIT License.
+ */
+
+// This file includes some known R5 syscalls
+// ToDo: maybe they should indeed do something...
+
+#include <SupportDefs.h>
+
+
+int _kset_mon_limit_(int num);
+int _kset_fd_limit_(int num);
+
+
+int
+_kset_mon_limit_(int num)
+{
+	return B_ERROR;
+}
+
+
+int
+_kset_fd_limit_(int num)
+{
+	return B_ERROR;
+}