diff --git a/src/tests/index.jai b/src/tests/index.jai
index 8d79d38..ade7e8a 100644
--- a/src/tests/index.jai
+++ b/src/tests/index.jai
@@ -1 +1,2 @@
 #load "utils.jai";
+#load "world_test.jai";
diff --git a/src/tests/world_test.jai b/src/tests/world_test.jai
new file mode 100644
index 0000000..6eacb15
--- /dev/null
+++ b/src/tests/world_test.jai
@@ -0,0 +1,65 @@
+test_floor_div_mod :: () {
+    s := begin_suite("floor_div / floor_mod");
+
+    check(*s, "floor_div( 0,  32) ==  0",  floor_div( 0,  32) ==  0);
+    check(*s, "floor_div( 1,  32) ==  0",  floor_div( 1,  32) ==  0);
+    check(*s, "floor_div(31,  32) ==  0",  floor_div(31,  32) ==  0);
+    check(*s, "floor_div(32,  32) ==  1",  floor_div(32,  32) ==  1);
+    check(*s, "floor_div(33,  32) ==  1",  floor_div(33,  32) ==  1);
+    check(*s, "floor_div(-1,  32) == -1",  floor_div(-1,  32) == -1);
+    check(*s, "floor_div(-32, 32) == -1",  floor_div(-32, 32) == -1);
+    check(*s, "floor_div(-33, 32) == -2",  floor_div(-33, 32) == -2);
+
+    check(*s, "floor_mod( 0,  32) ==  0",  floor_mod( 0,  32) ==  0);
+    check(*s, "floor_mod( 1,  32) ==  1",  floor_mod( 1,  32) ==  1);
+    check(*s, "floor_mod(31,  32) == 31",  floor_mod(31,  32) == 31);
+    check(*s, "floor_mod(32,  32) ==  0",  floor_mod(32,  32) ==  0);
+    check(*s, "floor_mod(33,  32) ==  1",  floor_mod(33,  32) ==  1);
+    check(*s, "floor_mod(-1,  32) == 31",  floor_mod(-1,  32) == 31);
+    check(*s, "floor_mod(-32, 32) ==  0",  floor_mod(-32, 32) ==  0);
+    check(*s, "floor_mod(-33, 32) == 31",  floor_mod(-33, 32) == 31);
+
+    end_suite(s);
+}
+
+test_coord_roundtrip :: () {
+    s := begin_suite("world coord round-trip");
+
+    roundtrip_check :: (suite: *Test_Suite, wx: s32, wy: s32, wz: s32) {
+        ck := world_to_chunk_coord(wx, wy, wz);
+        lx, ly, lz := world_to_local(wx, wy, wz);
+        rx, ry, rz := chunk_local_to_world(ck, lx, ly, lz);
+        check(suite, tprint("(%, %, %) round-trips", wx, wy, wz), rx == wx && ry == wy && rz == wz);
+    }
+
+    roundtrip_check(*s,   0,   0,   0);
+    roundtrip_check(*s,   1,   1,   1);
+    roundtrip_check(*s,  31,  31,  31);
+    roundtrip_check(*s,  32,  32,  32);
+    roundtrip_check(*s,  33,  33,  33);
+    roundtrip_check(*s,  -1,  -1,  -1);
+    roundtrip_check(*s, -32, -32, -32);
+    roundtrip_check(*s, -33, -33, -33);
+    roundtrip_check(*s,  63,  -1,  32);
+
+    end_suite(s);
+}
+
+test_chunk_coord_values :: () {
+    s := begin_suite("world_to_chunk_coord values");
+
+    check(*s, "( 0, 0, 0) -> chunk ( 0, 0, 0)", world_to_chunk_coord( 0,  0,  0) == .{ 0,  0,  0});
+    check(*s, "(31, 0, 0) -> chunk ( 0, 0, 0)", world_to_chunk_coord(31,  0,  0) == .{ 0,  0,  0});
+    check(*s, "(32, 0, 0) -> chunk ( 1, 0, 0)", world_to_chunk_coord(32,  0,  0) == .{ 1,  0,  0});
+    check(*s, "(-1, 0, 0) -> chunk (-1, 0, 0)", world_to_chunk_coord(-1,  0,  0) == .{-1,  0,  0});
+    check(*s, "(-32,0, 0) -> chunk (-1, 0, 0)", world_to_chunk_coord(-32, 0,  0) == .{-1,  0,  0});
+    check(*s, "(-33,0, 0) -> chunk (-2, 0, 0)", world_to_chunk_coord(-33, 0,  0) == .{-2,  0,  0});
+
+    end_suite(s);
+}
+
+#run {
+    test_floor_div_mod();
+    test_coord_roundtrip();
+    test_chunk_coord_values();
+}