diff --git a/src/arch/x86/isa/decoder/two_byte_opcodes.isa b/src/arch/x86/isa/decoder/two_byte_opcodes.isa
index 64920bcbd..c3fb5c19d 100644
--- a/src/arch/x86/isa/decoder/two_byte_opcodes.isa
+++ b/src/arch/x86/isa/decoder/two_byte_opcodes.isa
@@ -420,7 +420,11 @@
                 0x1: Inst::RDTSC();
                 0x2: Inst::RDMSR();
                 0x3: rdpmc();
+#if FULL_SYSTEM
                 0x4: sysenter();
+#else
+                0x4: SyscallInst::sysenter('xc->syscall(Rax)', IsSyscall);
+#endif
                 0x5: sysexit();
                 0x6: Inst::UD2();
                 0x7: getsec();