diff --git a/include/dungeon/dgn.h b/include/dungeon/dgn.h
index eef0dce..965c414 100644
--- a/include/dungeon/dgn.h
+++ b/include/dungeon/dgn.h
@@ -109,6 +109,8 @@ struct dgn {
 
 struct dgn *dgn_parse(uint8_t *data, size_t size);
 void dgn_free(struct dgn *dgn);
+
+int dgn_cell_index(struct dgn *dgn, uint32_t x, uint32_t y, uint32_t z);
 struct dgn_cell *dgn_cell_at(struct dgn *dgn, uint32_t x, uint32_t y, uint32_t z);
 
 static inline bool dgn_is_in_map(struct dgn *dgn, uint32_t x, uint32_t y, uint32_t z)
diff --git a/include/dungeon/map.h b/include/dungeon/map.h
index dde1b66..105e046 100644
--- a/include/dungeon/map.h
+++ b/include/dungeon/map.h
@@ -17,6 +17,7 @@
 #ifndef SYSTEM4_DUNGEON_MAP_H
 #define SYSTEM4_DUNGEON_MAP_H
 
+struct page;
 struct dungeon_context;
 struct dungeon_map;
 
@@ -32,5 +33,7 @@ void dungeon_map_set_cg(int surface, int index, int sprite);
 void dungeon_map_set_small_map_floor(int surface, int floor);
 void dungeon_map_set_large_map_floor(int surface, int floor);
 void dungeon_map_set_walked(int surface, int x, int y, int z, int flag);
+bool dungeon_map_load_walk_data(int surface, int map, struct page **page);
+bool dungeon_map_save_walk_data(int surface, int map, struct page **page);
 
 #endif /* SYSTEM4_DUNGEON_MAP_H */
diff --git a/src/dungeon/dgn.c b/src/dungeon/dgn.c
index c840e80..fa30762 100644
--- a/src/dungeon/dgn.c
+++ b/src/dungeon/dgn.c
@@ -114,9 +114,14 @@ void dgn_free(struct dgn *dgn)
 	free(dgn);
 }
 
-struct dgn_cell *dgn_cell_at(struct dgn *dgn, uint32_t x, uint32_t y, uint32_t z)
+int dgn_cell_index(struct dgn *dgn, uint32_t x, uint32_t y, uint32_t z)
 {
 	if (x >= dgn->size_x || y >= dgn->size_y || z >= dgn->size_z)
 		VM_ERROR("cell location out of range: (%d, %d, %d)", x, y, z);
-	return &dgn->cells[(z * dgn->size_y + y) * dgn->size_x + x];
+	return (z * dgn->size_y + y) * dgn->size_x + x;
+}
+
+struct dgn_cell *dgn_cell_at(struct dgn *dgn, uint32_t x, uint32_t y, uint32_t z)
+{
+	return &dgn->cells[dgn_cell_index(dgn, x, y, z)];
 }
diff --git a/src/dungeon/map.c b/src/dungeon/map.c
index 83e9d21..f2de17d 100644
--- a/src/dungeon/map.c
+++ b/src/dungeon/map.c
@@ -24,6 +24,7 @@
 #include "gfx/gfx.h"
 #include "sact.h"
 #include "vm.h"
+#include "vm/page.h"
 
 #ifndef M_PI
 #define M_PI (3.14159265358979323846)
@@ -56,6 +57,7 @@ struct dungeon_map {
 	int small_map_floor;
 	int large_map_floor;
 	bool all_visible;
+	int *walk_data;
 };
 
 struct dungeon_map *dungeon_map_create(void)
@@ -71,6 +73,7 @@ void dungeon_map_free(struct dungeon_map *map)
 	for (int i = 0; i < map->nr_textures; i++)
 		gfx_delete_texture(&map->textures[i]);
 	free(map->textures);
+	free(map->walk_data);
 	free(map);
 }
 
@@ -81,10 +84,11 @@ void dungeon_map_init(struct dungeon_context *ctx)
 
 	map->textures = xcalloc(dgn->size_y, sizeof(struct texture));
 	map->nr_textures = dgn->size_y;
-	for (int y = 0; y < dgn->size_y; y++) {
+	map->walk_data = xcalloc(dgn->size_x * dgn->size_y * dgn->size_z, sizeof(int));
+	for (uint32_t y = 0; y < dgn->size_y; y++) {
 		gfx_init_texture_rgba(&map->textures[y], dgn->size_x * CS, dgn->size_z * CS, (SDL_Color){0, 0, 0, 0});
-		for (int z = 0; z < dgn->size_z; z++) {
-			for (int x = 0; x < dgn->size_x; x++) {
+		for (uint32_t z = 0; z < dgn->size_z; z++) {
+			for (uint32_t x = 0; x < dgn->size_x; x++) {
 				dungeon_map_update_cell(ctx, x, y, z);
 			}
 		}
@@ -93,6 +97,7 @@ void dungeon_map_init(struct dungeon_context *ctx)
 
 static void reveal_cell(struct dungeon_context *ctx, int dgn_x, int dgn_y, int dgn_z)
 {
+	ctx->map->walk_data[dgn_cell_index(ctx->dgn, dgn_x, dgn_y, dgn_z)] = 1;
 	struct texture *dst = &ctx->map->textures[dgn_y];
 	int x = dgn_x * CS;
 	int y = (ctx->dgn->size_z - dgn_z - 1) * CS;
@@ -130,7 +135,7 @@ void dungeon_map_update_cell(struct dungeon_context *ctx, int dgn_x, int dgn_y,
 	else
 		gfx_fill(dst, x, y, CS, CS, 182, 72, 0);
 
-	const SDL_Color wall_colors[2] = {{255, 255, 255}, {255, 0, 0}};
+	const SDL_Color wall_colors[2] = {{255, 255, 255, 255}, {255, 0, 0, 255}};
 	if (cell->north_wall >= 0)
 		draw_hline(dst, x, y, CS, wall_colors[!!cell->enterable_north]);
 	if (cell->south_wall >= 0)
@@ -299,10 +304,119 @@ void dungeon_map_set_walked(int surface, int x, int y, int z, int flag)
 	reveal_cell(ctx, x, y, z);
 	if (x >= 0 && dgn_cell_at(ctx->dgn, x - 1, y, z)->floor < 0)
 		reveal_cell(ctx, x - 1, y, z);
-	if (x + 1 < ctx->dgn->size_x && dgn_cell_at(ctx->dgn, x + 1, y, z)->floor < 0)
+	if (x + 1u < ctx->dgn->size_x && dgn_cell_at(ctx->dgn, x + 1, y, z)->floor < 0)
 		reveal_cell(ctx, x + 1, y, z);
 	if (z >= 0 && dgn_cell_at(ctx->dgn, x, y, z - 1)->floor < 0)
 		reveal_cell(ctx, x, y, z - 1);
-	if (z + 1 < ctx->dgn->size_z && dgn_cell_at(ctx->dgn, x, y, z + 1)->floor < 0)
+	if (z + 1u < ctx->dgn->size_z && dgn_cell_at(ctx->dgn, x, y, z + 1)->floor < 0)
 		reveal_cell(ctx, x, y, z + 1);
 }
+
+/*
+ * WalkData serialization format (in Rance VI):
+ *
+ * struct WalkData {
+ *     int version;  // zero
+ *     int nr_maps;
+ *     struct {
+ *         int map_no;
+ *         int size_x, size_y, size_z;
+ *         int cells[size_x * size_y * size_z];
+ *     } maps[nr_maps];
+ * };
+ */
+
+enum {
+	WALK_DATA_NOT_FOUND = -1,
+	WALK_DATA_BROKEN = -2,
+};
+
+static int find_walk_data(struct page *array, int map_no, struct dgn *dgn)
+{
+	if (!array)
+		return WALK_DATA_BROKEN;
+	if (array->type != ARRAY_PAGE || array->a_type != AIN_ARRAY_INT || array->rank != 1)
+		VM_ERROR("Not a flat integer array");
+
+	int ptr = 0;
+	if (array->nr_vars < 2 || array->values[ptr++].i != 0)
+		return WALK_DATA_BROKEN;
+	int nr_maps = array->values[ptr++].i;
+
+	for (int i = 0; i < nr_maps; i++) {
+		if (array->nr_vars < ptr + 4)
+			return WALK_DATA_BROKEN;
+		int no = array->values[ptr].i;
+		uint32_t size_x = array->values[ptr + 1].i;
+		uint32_t size_y = array->values[ptr + 2].i;
+		uint32_t size_z = array->values[ptr + 3].i;
+		int nr_cells = size_x * size_y * size_z;
+		if (no == map_no) {
+			if (size_x != dgn->size_x || size_y != dgn->size_y || size_z != dgn->size_z)
+				return WALK_DATA_BROKEN;
+			if (ptr + 4 + nr_cells > array->nr_vars)
+				return WALK_DATA_BROKEN;
+			return ptr;
+		}
+		ptr += 4 + nr_cells;
+	}
+	return WALK_DATA_NOT_FOUND;
+}
+
+bool dungeon_map_load_walk_data(int surface, int map, struct page **page)
+{
+	struct dungeon_context *ctx = dungeon_get_context(surface);
+	if (!ctx || !ctx->dgn)
+		return false;
+	struct page *array = *page;
+
+	int offset = find_walk_data(array, map, ctx->dgn);
+	if (offset < 0)
+		return false;
+
+	offset += 4;
+	int i = 0;
+	for (uint32_t z = 0; z < ctx->dgn->size_z; z++) {
+		for (uint32_t y = 0; y < ctx->dgn->size_y; y++) {
+			for (uint32_t x = 0; x < ctx->dgn->size_x; x++) {
+				if (array->values[offset].i)
+					reveal_cell(ctx, x, y, z);
+				ctx->map->walk_data[i++] = array->values[offset++].i;
+			}
+		}
+	}
+
+	return true;
+}
+
+bool dungeon_map_save_walk_data(int surface, int map, struct page **page)
+{
+	struct dungeon_context *ctx = dungeon_get_context(surface);
+	if (!ctx || !ctx->dgn)
+		return false;
+	struct page *array = *page;
+	int nr_cells = ctx->dgn->size_x * ctx->dgn->size_y * ctx->dgn->size_z;
+
+	int offset = find_walk_data(array, map, ctx->dgn);
+	if (offset == WALK_DATA_NOT_FOUND) {
+		offset = array->nr_vars;
+		array->values[1].i += 1;
+		union vm_value dim = { .i = array->nr_vars + 4 + nr_cells };
+		*page = array = realloc_array(array, 1, &dim, AIN_ARRAY_INT, 0, false);
+	} else if (offset == WALK_DATA_BROKEN) {
+		if (array)
+			WARNING("Discarding broken walk data");
+		union vm_value dim = { .i = 2 + 4 + nr_cells };
+		*page = array = realloc_array(array, 1, &dim, AIN_ARRAY_INT, 0, false);
+		array->values[0].i = 0;
+		array->values[1].i = 1;
+		offset = 2;
+	}
+	array->values[offset++].i = map;
+	array->values[offset++].i = ctx->dgn->size_x;
+	array->values[offset++].i = ctx->dgn->size_y;
+	array->values[offset++].i = ctx->dgn->size_z;
+	for (int i = 0; i < nr_cells; i++)
+		array->values[offset++].i = ctx->map->walk_data[i];
+	return true;
+}
diff --git a/src/hll/DrawDungeon.c b/src/hll/DrawDungeon.c
index 8b4a922..86217cf 100644
--- a/src/hll/DrawDungeon.c
+++ b/src/hll/DrawDungeon.c
@@ -249,8 +249,6 @@ static int DrawDungeon_GetTexSound(int surface, int type, int num)
 
 HLL_WARN_UNIMPLEMENTED( , void, DrawDungeon, StopTimer, void);
 HLL_WARN_UNIMPLEMENTED( , void, DrawDungeon, RestartTimer, void);
-HLL_WARN_UNIMPLEMENTED(0, bool, DrawDungeon, LoadWalkData, int surface, int map, struct page **anWalkData);
-HLL_WARN_UNIMPLEMENTED(1, bool, DrawDungeon, SaveWalkData, int surface, int map, struct page **anWalkData);
 
 HLL_LIBRARY(DrawDungeon,
 			HLL_EXPORT(Init, DrawDungeon_Init),
@@ -369,6 +367,6 @@ HLL_LIBRARY(DrawDungeon,
 			HLL_EXPORT(GetTexSound, DrawDungeon_GetTexSound),
 			HLL_EXPORT(StopTimer, DrawDungeon_StopTimer),
 			HLL_EXPORT(RestartTimer, DrawDungeon_RestartTimer),
-			HLL_EXPORT(LoadWalkData, DrawDungeon_LoadWalkData),
-			HLL_EXPORT(SaveWalkData, DrawDungeon_SaveWalkData)
+			HLL_EXPORT(LoadWalkData, dungeon_map_load_walk_data),
+			HLL_EXPORT(SaveWalkData, dungeon_map_save_walk_data)
 			);