diff --git a/libvmi/libvmi_cdef.h b/libvmi/libvmi_cdef.h
index cb68f57..b3d058b 100644
--- a/libvmi/libvmi_cdef.h
+++ b/libvmi/libvmi_cdef.h
@@ -302,7 +302,7 @@ typedef struct x86_regs {
     uint64_t msr_lstar;
     uint64_t fs_base;
     uint64_t gs_base;
-    uint32_t cs_arbytes;
+    uint64_t cs_arbytes;
     ...;
 } x86_registers_t;