diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c
index 9d7f5afa..54d54e5e 100644
--- a/arch/arm64/kernel/syscall.c
+++ b/arch/arm64/kernel/syscall.c
@@ -2735,4 +2735,12 @@ void calculate_time_from_tsc(struct timespec *ts)
 		++ts->tv_sec;
 	}
 }
+
+extern void ptrace_syscall_event(struct thread *thread);
+long arch_ptrace_syscall_event(struct thread *thread,
+			       ihk_mc_user_context_t *ctx, long setret)
+{
+	ptrace_syscall_event(thread);
+	return setret;
+}
 /*** End of File ***/
diff --git a/arch/x86_64/kernel/syscall.c b/arch/x86_64/kernel/syscall.c
index e8a4b964..bd5664f9 100644
--- a/arch/x86_64/kernel/syscall.c
+++ b/arch/x86_64/kernel/syscall.c
@@ -2858,4 +2858,13 @@ void calculate_time_from_tsc(struct timespec *ts)
 		++ts->tv_sec;
 	}
 }
+
+extern void ptrace_syscall_event(struct thread *thread);
+long arch_ptrace_syscall_event(struct thread *thread,
+				ihk_mc_user_context_t *ctx, long setret)
+{
+	ihk_mc_syscall_ret(ctx) = setret;
+	ptrace_syscall_event(thread);
+	return ihk_mc_syscall_ret(ctx);
+}
 /*** End of File ***/
diff --git a/kernel/include/syscall.h b/kernel/include/syscall.h
index 3a5ccfd5..bc8369d9 100644
--- a/kernel/include/syscall.h
+++ b/kernel/include/syscall.h
@@ -586,6 +586,10 @@ typedef struct uti_attr {
 	uint64_t flags; /* Representing location and behavior hints by bitmap */
 } uti_attr_t;
 
+struct thread;
+long arch_ptrace_syscall_event(struct thread *thread,
+			       ihk_mc_user_context_t *ctx, long setret);
+
 struct uti_ctx {
 	union {
 		char ctx[4096];
diff --git a/kernel/syscall.c b/kernel/syscall.c
index ca851c6b..1e4c6937 100644
--- a/kernel/syscall.c
+++ b/kernel/syscall.c
@@ -2273,7 +2273,7 @@ static int ptrace_report_exec(struct thread *thread)
 	return 0;
 }
 
-static void ptrace_syscall_event(struct thread *thread)
+void ptrace_syscall_event(struct thread *thread)
 {
 	int ptrace = thread->ptrace;
 
@@ -2551,8 +2551,7 @@ SYSCALL_DECLARE(execve)
 	}
 
 	if (thread->ptrace) {
-		ihk_mc_syscall_ret(ctx) = 0;
-		ptrace_syscall_event(thread);
+		arch_ptrace_syscall_event(thread, ctx, 0);
 	}
 
 	/* Unmap all memory areas of the process, userspace will be gone */
@@ -9619,6 +9618,9 @@ long syscall(int num, ihk_mc_user_context_t *ctx)
 
 	if(cpu_local_var(current)->proc->status == PS_EXITED &&
 	   (num != __NR_exit && num != __NR_exit_group)){
+		/* x86_64: Setting -EINVAL to rax is done in the
+		 * following return.
+		 */
 		save_syscall_return_value(num, -EINVAL);
 		check_signal(-EINVAL, NULL, -1);
 		set_cputime(CPUTIME_MODE_K2U);
@@ -9628,8 +9630,8 @@ long syscall(int num, ihk_mc_user_context_t *ctx)
 	cpu_enable_interrupt();
 
 	if (cpu_local_var(current)->ptrace) {
-		ihk_mc_syscall_ret(ctx) = -ENOSYS;
-		ptrace_syscall_event(cpu_local_var(current));
+		arch_ptrace_syscall_event(cpu_local_var(current),
+					  ctx, -ENOSYS);
 		num = ihk_mc_syscall_number(ctx);
 	}
 
@@ -9675,11 +9677,15 @@ long syscall(int num, ihk_mc_user_context_t *ctx)
 	}
 
 	if (cpu_local_var(current)->ptrace) {
-		ihk_mc_syscall_ret(ctx) = l;
-		ptrace_syscall_event(cpu_local_var(current));
-		l = ihk_mc_syscall_ret(ctx);
+		/* arm64: The return value modified by the tracer is
+		 * stored to x0 in the following check_signal().
+		 */
+		l = arch_ptrace_syscall_event(cpu_local_var(current), ctx, l);
 	}
 
+	/* x86_64: Setting l to rax is done in the
+	 * following return.
+	 */
 	save_syscall_return_value(num, l);
 
 #ifdef PROFILE_ENABLE