diff --git a/kernel/include/process.h b/kernel/include/process.h
index 2cc627b8..4cba5b22 100644
--- a/kernel/include/process.h
+++ b/kernel/include/process.h
@@ -578,7 +578,8 @@ struct process {
 	int nr_processes; /* For partitioned execution */
 	int process_rank; /* Rank in partition */
 
-	void *fd_priv_table[256];
+#define MAX_FD_PRIV 256
+	void *fd_priv_table[MAX_FD_PRIV];
 	/* HFI1 specific */
 	void *hfi1_kregbase;
 	void *hfi1_piobase;
diff --git a/kernel/process.c b/kernel/process.c
index 4bdb9577..68461197 100644
--- a/kernel/process.c
+++ b/kernel/process.c
@@ -140,7 +140,7 @@ init_process(struct process *proc, struct process *parent)
 #endif /* POSTK_DEBUG_ARCH_DEP_63 */
 
 	// Double check the inheritance from parent
-	memset(proc->fd_priv_table, 0, 256 * sizeof(void *));
+	memset(proc->fd_priv_table, 0, MAX_FD_PRIV * sizeof(void *));
 
 	INIT_LIST_HEAD(&proc->threads_list);
 	INIT_LIST_HEAD(&proc->children_list);
diff --git a/kernel/syscall.c b/kernel/syscall.c
index 60e41b57..9459379f 100644
--- a/kernel/syscall.c
+++ b/kernel/syscall.c
@@ -485,7 +485,9 @@ long do_syscall(struct syscall_request *req, int cpu, int pid)
 				res.private_data &&
 				!strncmp((const char *)req->args[0], "/dev/hfi", 8)) {
 
-			thread->proc->fd_priv_table[rc] = res.private_data;
+			if (rc >= 0 && rc < MAX_FD_PRIV) {
+				thread->proc->fd_priv_table[rc] = res.private_data;
+			}
 			dkprintf("%s: PID: %d, open fd: %d, filename: "
 					"%s, private_data: 0x%lx\n",
 					__FUNCTION__, thread->proc->pid,
@@ -3140,7 +3142,8 @@ SYSCALL_DECLARE(writev)
 	int fd = ihk_mc_syscall_arg0(ctx);
 	struct iovec *iovec = (struct iovec *)ihk_mc_syscall_arg1(ctx);
 	int iovcnt = ihk_mc_syscall_arg2(ctx);
-	void *private_data = proc->fd_priv_table[fd];
+	void *private_data = (fd < 0 || fd >= MAX_FD_PRIV) ? NULL : proc->fd_priv_table[fd];
+
 	if (private_data) {
 		return hfi1_aio_write(private_data, iovec, iovcnt);
 	}
@@ -3182,7 +3185,7 @@ SYSCALL_DECLARE(ioctl)
 	struct process *proc = thread->proc;
 	struct mckfd *fdp;
 	long irqstate;
-	void *private_data = proc->fd_priv_table[fd];
+	void *private_data = (fd < 0 || fd >= MAX_FD_PRIV) ? NULL : proc->fd_priv_table[fd];
 	unsigned long t_s = rdtsc();
 	int sub_rc = 0;
 
@@ -3342,7 +3345,7 @@ SYSCALL_DECLARE(close)
 		rc = syscall_generic_forwarding(__NR_close, ctx);
 	}
 
-	if (fd < 256) {
+	if (fd >= 0 && fd < MAX_FD_PRIV) {
 		thread->proc->fd_priv_table[fd] = NULL;
 	}