diff --git a/src/aarch64/context.rs b/src/aarch64/context.rs
index f2535be..eb56985 100644
--- a/src/aarch64/context.rs
+++ b/src/aarch64/context.rs
@@ -14,7 +14,7 @@ pub struct TrapFrame {
     pub spsr: u64,
 
     /// make sure the size is 16 bytes aligned
-    pub __pad: [u8; 8],
+    pub __pad: u64,
 }
 
 impl fmt::Debug for TrapFrame {
diff --git a/src/aarch64/trap.S b/src/aarch64/trap.S
index 09354be..a938aa2 100644
--- a/src/aarch64/trap.S
+++ b/src/aarch64/trap.S
@@ -97,8 +97,8 @@ exception_vector_base:
 
     mrs     x8, sp_el0
     mrs     x9, tpidr_el0
-    ldp     x10, x11, [x1, 33 * 8]
-    stp     x8, x9, [x1, 33 * 8]
+    ldp     x10, x11, [x1, {trapframe_size}]
+    stp     x8, x9, [x1, {trapframe_size}]
     mov     sp, x10
     msr     tpidr_el0, x11
 
@@ -124,8 +124,8 @@ enter_user:
 
     mov     x10, sp
     mrs     x11, tpidr_el0
-    ldp     x8, x9, [x0, 33 * 8]
-    stp     x10, x11, [x0, 33 * 8]
+    ldp     x8, x9, [x0, {trapframe_size}]
+    stp     x10, x11, [x0,{trapframe_size}]
     msr     sp_el0, x8
     msr     tpidr_el0, x9
 
diff --git a/src/aarch64/uspace.rs b/src/aarch64/uspace.rs
index 67042f9..347c3dc 100644
--- a/src/aarch64/uspace.rs
+++ b/src/aarch64/uspace.rs
@@ -39,7 +39,7 @@ impl UserContext {
                     + SPSR_EL1::I::Unmasked
                     + SPSR_EL1::F::Masked)
                     .value,
-                __pad: [0; 8],
+                __pad: 0,
             },
             sp: ustack_top.as_usize() as _,
             tpidr: 0,