diff --git a/repos/base-hw/src/core/spec/x86_64/idt.cc b/repos/base-hw/src/core/spec/x86_64/idt.cc
index d10ed702a..ffffc8319 100644
--- a/repos/base-hw/src/core/spec/x86_64/idt.cc
+++ b/repos/base-hw/src/core/spec/x86_64/idt.cc
@@ -4,14 +4,14 @@
 #include "idt.h"
 
 extern int _mt_idt;
+extern int _mt_isrs;
 
 using namespace Genode;
 
 
 void Idt::setup(addr_t const virt_base)
 {
-	/* TODO: Calculate from _mt_isrs label */
-	uint64_t base = 0;
+	int base = _virt_mtc_addr(virt_base, (addr_t)&_mt_isrs);
 
 	for (unsigned vec = 0; vec < SIZE_IDT; vec++) {
 		/* ISRs are padded to 4 bytes */
@@ -20,8 +20,9 @@ void Idt::setup(addr_t const virt_base)
 		_table[vec].offset_15_00 = base & 0xffff;
 		_table[vec].segment_sel  = 8;
 		_table[vec].flags        = 0x8e00;
-		_table[vec].offset_31_16 = (base >> 16) & 0xffff;
-		_table[vec].offset_63_32 = (base >> 32) & 0xffff;
+		/* Assume base to be below address 0x10000 */
+		_table[vec].offset_31_16 = 0;
+		_table[vec].offset_63_32 = 0;
 	}
 
 	/* Set DPL of syscall entry to 3 */