diff --git a/src/unix/linux_like/android/b64/aarch64/mod.rs b/src/unix/linux_like/android/b64/aarch64/mod.rs
index 3c6131089ee89..f9a4c4814eb98 100644
--- a/src/unix/linux_like/android/b64/aarch64/mod.rs
+++ b/src/unix/linux_like/android/b64/aarch64/mod.rs
@@ -67,14 +67,13 @@ s! {
         pub uc_mcontext: mcontext_t,
     }
 
-    #[repr(align(16))]
     pub struct mcontext_t {
         pub fault_address: c_ulonglong,
         pub regs: [c_ulonglong; 31],
         pub sp: c_ulonglong,
         pub pc: c_ulonglong,
         pub pstate: c_ulonglong,
-        __reserved: [u64; 512],
+        pub __reserved: [u128; 256],
     }
 
     pub struct user_fpsimd_struct {
diff --git a/src/unix/linux_like/linux/gnu/b64/aarch64/mod.rs b/src/unix/linux_like/linux/gnu/b64/aarch64/mod.rs
index b5af0e8ec9548..316d68d85b609 100644
--- a/src/unix/linux_like/linux/gnu/b64/aarch64/mod.rs
+++ b/src/unix/linux_like/linux/gnu/b64/aarch64/mod.rs
@@ -212,14 +212,13 @@ s! {
         pub uc_mcontext: mcontext_t,
     }
 
-    #[repr(align(16))]
     pub struct mcontext_t {
         pub fault_address: c_ulonglong,
         pub regs: [c_ulonglong; 31],
         pub sp: c_ulonglong,
         pub pc: c_ulonglong,
         pub pstate: c_ulonglong,
-        __reserved: [u64; 512],
+        pub __reserved: [u128; 256],
     }
 
     pub struct user_fpsimd_struct {
diff --git a/src/unix/linux_like/linux/musl/b64/aarch64/mod.rs b/src/unix/linux_like/linux/musl/b64/aarch64/mod.rs
index 087e39001e84f..78e91560019d4 100644
--- a/src/unix/linux_like/linux/musl/b64/aarch64/mod.rs
+++ b/src/unix/linux_like/linux/musl/b64/aarch64/mod.rs
@@ -96,14 +96,13 @@ s! {
         pub uc_mcontext: mcontext_t,
     }
 
-    #[repr(align(16))]
     pub struct mcontext_t {
         pub fault_address: c_ulong,
         pub regs: [c_ulong; 31],
         pub sp: c_ulong,
         pub pc: c_ulong,
         pub pstate: c_ulong,
-        __reserved: [u64; 512],
+        pub __reserved: [u128; 256],
     }
 
     #[repr(align(8))]