diff --git a/src/main/kotlin/ru/dbotthepony/mc/otm/core/collect/BlockPosSet.kt b/src/main/kotlin/ru/dbotthepony/mc/otm/core/collect/BlockPosSet.kt
index b42bfdd85..a4a24cc32 100644
--- a/src/main/kotlin/ru/dbotthepony/mc/otm/core/collect/BlockPosSet.kt
+++ b/src/main/kotlin/ru/dbotthepony/mc/otm/core/collect/BlockPosSet.kt
@@ -88,7 +88,7 @@ class BlockPosSet : MutableSet<BlockPos> {
 	fun subset(pos: ChunkPos): Set<BlockPos> {
 		val result = BlockPosSet()
 
-		for (key in segments.keys.iterator(SectionPos.of(pos.x, 0, pos.z))) {
+		for (key in segments.keys.iterator(SectionPos.of(pos.x, Int.MIN_VALUE, pos.z))) {
 			if (key.x != pos.x || key.z != pos.z) break
 			result.segments[key] = segments[key]
 		}
@@ -192,4 +192,16 @@ class BlockPosSet : MutableSet<BlockPos> {
 	override fun retainAll(elements: Collection<BlockPos>): Boolean {
 		return removeIf { it !in elements }
 	}
+
+	override fun equals(other: Any?): Boolean {
+		return this === other || other is Set<*> && other.size == size && other.containsAll(this)
+	}
+
+	override fun hashCode(): Int {
+		return segments.hashCode()
+	}
+
+	override fun toString(): String {
+		return "BlockPosSet[${joinToString(", ")}]"
+	}
 }
diff --git a/src/test/kotlin/ru/dbotthepony/mc/otm/tests/BlockPosSetTests.kt b/src/test/kotlin/ru/dbotthepony/mc/otm/tests/BlockPosSetTests.kt
new file mode 100644
index 000000000..a67f2f102
--- /dev/null
+++ b/src/test/kotlin/ru/dbotthepony/mc/otm/tests/BlockPosSetTests.kt
@@ -0,0 +1,91 @@
+package ru.dbotthepony.mc.otm.tests
+
+import it.unimi.dsi.fastutil.objects.ObjectArraySet
+import net.minecraft.core.BlockPos
+import net.minecraft.core.SectionPos
+import net.minecraft.world.level.ChunkPos
+import org.junit.jupiter.api.Assertions
+import org.junit.jupiter.api.DisplayName
+import org.junit.jupiter.api.Test
+import ru.dbotthepony.mc.otm.core.collect.BlockPosSet
+import ru.dbotthepony.mc.otm.core.util.GJRAND64RandomSource
+import java.util.stream.Collectors
+
+object BlockPosSetTests {
+	@Test
+	@DisplayName("BlockPosSet additions")
+	fun add() {
+		val rand = GJRAND64RandomSource(43752304058048234L, -29394036784594328L)
+
+		val positions = ObjectArraySet<BlockPos>()
+
+		for (i in 0 until 1000) {
+			val x = rand.nextInt(-200, 200)
+			val y = rand.nextInt(-200, 200)
+			val z = rand.nextInt(-200, 200)
+			positions.add(BlockPos(x, y, z))
+		}
+
+		val result = BlockPosSet()
+		result.addAll(positions)
+
+		Assertions.assertEquals(positions, result)
+		Assertions.assertEquals(positions, ObjectArraySet(result))
+
+		run {
+			val expected = positions.stream().filter { SectionPos.blockToSectionCoord(it.x) == 0 && SectionPos.blockToSectionCoord(it.z) == 0 }.collect(Collectors.toCollection(::ObjectArraySet))
+			val actual = result.subset(ChunkPos.ZERO)
+
+			Assertions.assertEquals(expected, actual)
+			Assertions.assertEquals(expected, ObjectArraySet(actual))
+		}
+
+		run {
+			val expected = positions.stream().filter { SectionPos.blockToSectionCoord(it.x) == 0 && SectionPos.blockToSectionCoord(it.z) == 1 }.collect(Collectors.toCollection(::ObjectArraySet))
+			val actual = result.subset(ChunkPos(0, 1))
+
+			Assertions.assertEquals(expected, actual)
+			Assertions.assertEquals(expected, ObjectArraySet(actual))
+		}
+
+		run {
+			val expected = positions.stream().filter { SectionPos.blockToSectionCoord(it.x) == 0 && SectionPos.blockToSectionCoord(it.z) == -1 }.collect(Collectors.toCollection(::ObjectArraySet))
+			val actual = result.subset(ChunkPos(0, -1))
+
+			Assertions.assertEquals(expected, actual)
+			Assertions.assertEquals(expected, ObjectArraySet(actual))
+		}
+
+		run {
+			val expected = positions.stream().filter { SectionPos.blockToSectionCoord(it.x) == 1 && SectionPos.blockToSectionCoord(it.z) == 0 }.collect(Collectors.toCollection(::ObjectArraySet))
+			val actual = result.subset(ChunkPos(1, 0))
+
+			Assertions.assertEquals(expected, actual)
+			Assertions.assertEquals(expected, ObjectArraySet(actual))
+		}
+
+		run {
+			val expected = positions.stream().filter { SectionPos.blockToSectionCoord(it.x) == -1 && SectionPos.blockToSectionCoord(it.z) == 0 }.collect(Collectors.toCollection(::ObjectArraySet))
+			val actual = result.subset(ChunkPos(-1, 0))
+
+			Assertions.assertEquals(expected, actual)
+			Assertions.assertEquals(expected, ObjectArraySet(actual))
+		}
+
+		run {
+			val expected = positions.stream().filter { SectionPos.blockToSectionCoord(it.x) == 1 && SectionPos.blockToSectionCoord(it.z) == 1 }.collect(Collectors.toCollection(::ObjectArraySet))
+			val actual = result.subset(ChunkPos(1, 1))
+
+			Assertions.assertEquals(expected, actual)
+			Assertions.assertEquals(expected, ObjectArraySet(actual))
+		}
+
+		run {
+			val expected = positions.stream().filter { SectionPos.blockToSectionCoord(it.x) == -1 && SectionPos.blockToSectionCoord(it.z) == 1 }.collect(Collectors.toCollection(::ObjectArraySet))
+			val actual = result.subset(ChunkPos(-1, 1))
+
+			Assertions.assertEquals(expected, actual)
+			Assertions.assertEquals(expected, ObjectArraySet(actual))
+		}
+	}
+}