diff --git a/kernel/handle.c b/kernel/handle.c
index d92f025..464b28c 100644
--- a/kernel/handle.c
+++ b/kernel/handle.c
@@ -6,7 +6,8 @@
 #include <kernel/vm.h>
 
 /* depth=3 gives a maximum of ~66.6 million handles */
-#define MAX_TABLE_DEPTH 3
+#define MAX_TABLE_DEPTH  3
+#define RESERVED_HANDLES 64
 
 static struct vm_cache handle_table_cache = {
 	.c_name = "handle_table",
@@ -38,7 +39,6 @@ static kern_status_t decode_handle_indices(
 	kern_handle_t handle,
 	unsigned int indices[MAX_TABLE_DEPTH])
 {
-	handle >>= 2;
 	for (int i = 0; i < MAX_TABLE_DEPTH; i++) {
 		unsigned int div = (i > 0 ? REFS_PER_TABLE : HANDLES_PER_TABLE);
 
@@ -63,8 +63,6 @@ static kern_status_t encode_handle_indices(
 		mul *= REFS_PER_TABLE;
 	}
 
-	handle <<= 2;
-
 	*out_handle = handle;
 	return KERN_OK;
 }
@@ -76,6 +74,7 @@ kern_status_t handle_table_alloc_handle(
 {
 	int i;
 	unsigned int indices[MAX_TABLE_DEPTH] = {0};
+	static const unsigned int reserved_indices[MAX_TABLE_DEPTH] = {0};
 
 	for (i = 0; i < MAX_TABLE_DEPTH - 1; i++) {
 		unsigned int next_index = bitmap_lowest_clear(
@@ -101,6 +100,10 @@ kern_status_t handle_table_alloc_handle(
 		tab = next;
 	}
 
+	if (memcmp(indices, reserved_indices, sizeof indices) == 0) {
+		bitmap_fill(tab->t_handles.t_handle_map, RESERVED_HANDLES);
+	}
+
 	unsigned int handle_index = bitmap_lowest_clear(
 		tab->t_handles.t_handle_map,
 		HANDLES_PER_TABLE);
@@ -119,11 +122,13 @@ kern_status_t handle_table_alloc_handle(
 	return encode_handle_indices(indices, out_handle);
 }
 
-void handle_table_free_handle(struct handle_table *tab, kern_handle_t handle)
+kern_status_t handle_table_free_handle(
+	struct handle_table *tab,
+	kern_handle_t handle)
 {
 	unsigned int indices[MAX_TABLE_DEPTH];
 	if (decode_handle_indices(handle, indices) != KERN_OK) {
-		return;
+		return KERN_NO_ENTRY;
 	}
 
 	int i;
@@ -131,7 +136,7 @@ void handle_table_free_handle(struct handle_table *tab, kern_handle_t handle)
 		struct handle_table *next
 			= tab->t_subtables.t_subtable_list[indices[i]];
 		if (!next) {
-			return;
+			return KERN_NO_ENTRY;
 		}
 
 		bitmap_clear(tab->t_subtables.t_subtable_map, indices[i]);
@@ -139,6 +144,10 @@ void handle_table_free_handle(struct handle_table *tab, kern_handle_t handle)
 	}
 
 	unsigned int handle_index = indices[i];
+	if (!bitmap_check(tab->t_handles.t_handle_map, handle_index)) {
+		return KERN_NO_ENTRY;
+	}
+
 	bitmap_clear(tab->t_handles.t_handle_map, handle_index);
 	struct handle *handle_entry
 		= &tab->t_handles.t_handle_list[handle_index];
@@ -148,6 +157,7 @@ void handle_table_free_handle(struct handle_table *tab, kern_handle_t handle)
 	}
 
 	memset(handle_entry, 0x0, sizeof *handle_entry);
+	return KERN_OK;
 }
 
 struct handle *handle_table_get_handle(