diff --git a/db-sqlite3.cpp b/db-sqlite3.cpp
index f75a998..b7416f3 100644
--- a/db-sqlite3.cpp
+++ b/db-sqlite3.cpp
@@ -62,8 +62,8 @@ void DBSQLite3::getBlocksOnZ(std::map<int16_t, BlockList> &blocks, int16_t zPos)
 	int result;
 
 	// Magic numbers!
-	int64_t minPos = (zPos * 0x1000000) - 0x800000;
-	int64_t maxPos = (zPos * 0x1000000) + 0x7FFFFF;
+	int64_t minPos = encodeBlockPos(BlockPos(0, -2048, zPos));
+	int64_t maxPos = encodeBlockPos(BlockPos(0, 2048, zPos)) - 1;
 
 	SQLOK(bind_int64(stmt_get_blocks_z, 1, minPos));
 	SQLOK(bind_int64(stmt_get_blocks_z, 2, maxPos));
diff --git a/db.h b/db.h
index 40770b0..aaf43ac 100644
--- a/db.h
+++ b/db.h
@@ -16,6 +16,8 @@ public:
 	int16_t y;
 	int16_t z;
 
+	BlockPos() : x(0), y(0), z(0) {}
+	BlockPos(int16_t x, int16_t y, int16_t z) : x(x), y(y), z(z) {}
 	bool operator < (const BlockPos &p) const
 	{
 		if (z > p.z) {