diff --git a/repos/base-hw/src/core/spec/x86_64/mode_transition.s b/repos/base-hw/src/core/spec/x86_64/mode_transition.s
index b78f5b222..a3c742d9c 100644
--- a/repos/base-hw/src/core/spec/x86_64/mode_transition.s
+++ b/repos/base-hw/src/core/spec/x86_64/mode_transition.s
@@ -20,6 +20,13 @@
 /* globally mapped buffer storage */
 .set BUFFER_SIZE, 6 * 8
 
+/* offsets of the member variables in a CPU context */
+.set SP_OFFSET,     1 * 8
+.set R8_OFFSET,     2 * 8
+.set RAX_OFFSET,   10 * 8
+.set FLAGS_OFFSET, 18 * 8
+.set CR3_OFFSET,   20 * 8
+
 .section .text
 
 	/*