diff --git a/tools/regz/src/Database.zig b/tools/regz/src/Database.zig
index 7586d06..d9b8dad 100644
--- a/tools/regz/src/Database.zig
+++ b/tools/regz/src/Database.zig
@@ -303,6 +303,8 @@ pub fn createEntity(db: *Database) EntityId {
 }
 
 pub fn destroyEntity(db: *Database, id: EntityId) void {
+    // note that if something can be a child, you must remove it from the child
+    // set of its parent
     switch (db.getEntityType(id) orelse return) {
         .register => {
             log.debug("{}: destroying register", .{id});
@@ -318,9 +320,15 @@ pub fn destroyEntity(db: *Database, id: EntityId) void {
             // TODO: remove fields
             _ = db.types.registers.swapRemove(id);
         },
+        .peripheral => {
+            log.debug("{}: destroying peripheral", .{id});
+            // TODO: remove children
+            _ = db.types.peripherals.swapRemove(id);
+        },
         else => {},
     }
 
+    db.removeChildren(id);
     db.removeAttrs(id);
 }
 
@@ -335,6 +343,22 @@ fn removeAttrs(db: *Database, id: EntityId) void {
     }
 }
 
+fn removeChildren(db: *Database, id: EntityId) void {
+    inline for (@typeInfo(TypeOfField(Database, "children")).Struct.fields) |field| {
+        if (@field(db.children, field.name).fetchSwapRemove(id)) |children_entry| {
+            var children_set = children_entry.value;
+            defer children_set.deinit(db.gpa);
+
+            var it = children_set.iterator();
+            while (it.next()) |child_entry| {
+                const child_id = child_entry.key_ptr.*;
+                // this will get rid of the parent attr
+                db.destroyEntity(child_id);
+            }
+        }
+    }
+}
+
 pub fn createDevice(
     db: *Database,
     opts: struct {
@@ -781,7 +805,6 @@ pub fn getEntityIdByName(
     comptime var group = (tok_it.next() orelse unreachable) ++ "s";
     comptime var table = (tok_it.next() orelse unreachable) ++ "s";
 
-    log.debug("group: {s}, table: {s}", .{ group, table });
     var it = @field(@field(db, group), table).iterator();
     return while (it.next()) |entry| {
         const entry_id = entry.key_ptr.*;
diff --git a/tools/regz/src/gen.zig b/tools/regz/src/gen.zig
index 43387e2..d838471 100644
--- a/tools/regz/src/gen.zig
+++ b/tools/regz/src/gen.zig
@@ -252,7 +252,7 @@ fn writePeripheralInstance(db: Database, instance_id: EntityId, offset: u64, out
     else
         "";
 
-    try writer.print("pub const {s} = @ptrCast(*volatile {s}{s}, 0x{x});\n", .{
+    try writer.print("pub const {s} = @intToPtr(*volatile {s}{s}, 0x{x});\n", .{
         std.zig.fmtId(name),
         array_prefix,
         type_ref,
@@ -918,7 +918,7 @@ test "gen.peripheral instantiation" {
         \\pub const devices = struct {
         \\    pub const TEST_DEVICE = struct {
         \\        pub const peripherals = struct {
-        \\            pub const TEST0 = @ptrCast(*volatile types.TEST_PERIPHERAL, 0x1000);
+        \\            pub const TEST0 = @intToPtr(*volatile types.TEST_PERIPHERAL, 0x1000);
         \\        };
         \\    };
         \\};
@@ -950,8 +950,8 @@ test "gen.peripherals with a shared type" {
         \\pub const devices = struct {
         \\    pub const TEST_DEVICE = struct {
         \\        pub const peripherals = struct {
-        \\            pub const TEST0 = @ptrCast(*volatile types.TEST_PERIPHERAL, 0x1000);
-        \\            pub const TEST1 = @ptrCast(*volatile types.TEST_PERIPHERAL, 0x2000);
+        \\            pub const TEST0 = @intToPtr(*volatile types.TEST_PERIPHERAL, 0x1000);
+        \\            pub const TEST1 = @intToPtr(*volatile types.TEST_PERIPHERAL, 0x2000);
         \\        };
         \\    };
         \\};
@@ -1158,8 +1158,8 @@ test "gen.namespaced register groups" {
         \\pub const devices = struct {
         \\    pub const ATmega328P = struct {
         \\        pub const peripherals = struct {
-        \\            pub const PORTB = @ptrCast(*volatile types.PORT.PORTB, 0x23);
-        \\            pub const PORTC = @ptrCast(*volatile types.PORT.PORTC, 0x26);
+        \\            pub const PORTB = @intToPtr(*volatile types.PORT.PORTB, 0x23);
+        \\            pub const PORTC = @intToPtr(*volatile types.PORT.PORTC, 0x26);
         \\        };
         \\    };
         \\};
@@ -1198,7 +1198,7 @@ test "gen.peripheral with reserved register" {
         \\pub const devices = struct {
         \\    pub const ATmega328P = struct {
         \\        pub const peripherals = struct {
-        \\            pub const PORTB = @ptrCast(*volatile types.PORTB, 0x23);
+        \\            pub const PORTB = @intToPtr(*volatile types.PORTB, 0x23);
         \\        };
         \\    };
         \\};
@@ -1229,7 +1229,7 @@ test "gen.peripheral with count" {
         \\pub const devices = struct {
         \\    pub const ATmega328P = struct {
         \\        pub const peripherals = struct {
-        \\            pub const PORTB = @ptrCast(*volatile [4]types.PORTB, 0x23);
+        \\            pub const PORTB = @intToPtr(*volatile [4]types.PORTB, 0x23);
         \\        };
         \\    };
         \\};
@@ -1260,7 +1260,7 @@ test "gen.peripheral with count, padding required" {
         \\pub const devices = struct {
         \\    pub const ATmega328P = struct {
         \\        pub const peripherals = struct {
-        \\            pub const PORTB = @ptrCast(*volatile [4]types.PORTB, 0x23);
+        \\            pub const PORTB = @intToPtr(*volatile [4]types.PORTB, 0x23);
         \\        };
         \\    };
         \\};
@@ -1292,7 +1292,7 @@ test "gen.register with count" {
         \\pub const devices = struct {
         \\    pub const ATmega328P = struct {
         \\        pub const peripherals = struct {
-        \\            pub const PORTB = @ptrCast(*volatile types.PORTB, 0x23);
+        \\            pub const PORTB = @intToPtr(*volatile types.PORTB, 0x23);
         \\        };
         \\    };
         \\};
@@ -1323,7 +1323,7 @@ test "gen.register with count and fields" {
         \\pub const devices = struct {
         \\    pub const ATmega328P = struct {
         \\        pub const peripherals = struct {
-        \\            pub const PORTB = @ptrCast(*volatile types.PORTB, 0x23);
+        \\            pub const PORTB = @intToPtr(*volatile types.PORTB, 0x23);
         \\        };
         \\    };
         \\};
diff --git a/tools/regz/src/main.zig b/tools/regz/src/main.zig
index 88223a6..640d51a 100644
--- a/tools/regz/src/main.zig
+++ b/tools/regz/src/main.zig
@@ -137,7 +137,10 @@ fn mainImpl() anyerror!void {
 
     var buffered = std.io.bufferedWriter(raw_writer);
     if (res.args.json)
-        try db.jsonStringify(.{}, buffered.writer())
+        try db.jsonStringify(
+            .{ .whitespace = .{ .indent = .{ .Space = 2 } } },
+            buffered.writer(),
+        )
     else
         try db.toZig(buffered.writer());
 
diff --git a/tools/regz/src/svd.zig b/tools/regz/src/svd.zig
index 32af2f4..8689c97 100644
--- a/tools/regz/src/svd.zig
+++ b/tools/regz/src/svd.zig
@@ -164,7 +164,13 @@ pub fn loadIntoDb(db: *Database, doc: xml.Doc) !void {
         const id = derived_entry.key_ptr.*;
         const derived_name = derived_entry.value_ptr.*;
 
-        try deriveEntity(ctx.db.*, id, derived_name);
+        deriveEntity(ctx, id, derived_name) catch |err| {
+            log.warn("failed to derive entity {} from {s}: {}", .{
+                id,
+                derived_name,
+                err,
+            });
+        };
     }
 
     db.assertValid();
@@ -225,10 +231,43 @@ fn archFromStr(str: []const u8) Database.Arch {
         .unknown;
 }
 
-pub fn deriveEntity(db: Database, id: EntityId, derived_name: []const u8) !void {
+pub fn deriveEntity(ctx: Context, id: EntityId, derived_name: []const u8) !void {
+    const db = ctx.db;
     log.debug("{}: derived from {s}", .{ id, derived_name });
     const entity_type = db.getEntityType(id);
-    log.warn("TODO: implement derivation for {?}", .{entity_type});
+    assert(entity_type != null);
+    switch (entity_type.?) {
+        .peripheral => {
+            // TODO: what do we do when we have other fields set? maybe make
+            // some assertions and then skip if we're not sure
+            const name = db.attrs.name.get(id);
+            const base_instance_id = try db.getEntityIdByName("instance.peripheral", derived_name);
+            const base_id = db.instances.peripherals.get(base_instance_id) orelse return error.PeripheralNotFound;
+
+            if (ctx.derived_entities.contains(base_id)) {
+                log.warn("TODO: chained peripheral derivation: {?s}", .{name});
+                return error.TodoChainedDerivation;
+            }
+
+            if (try db.instances.peripherals.fetchPut(db.gpa, id, base_id)) |entry| {
+                const maybe_remove_peripheral_id = entry.value;
+                var it = db.instances.peripherals.iterator();
+                while (it.next()) |instance_entry| {
+                    const used_peripheral_id = instance_entry.value_ptr.*;
+
+                    // if there is a match don't delete the entity
+                    if (used_peripheral_id == maybe_remove_peripheral_id)
+                        break;
+                } else {
+                    // no instance is using this peripheral so we can remove it
+                    db.destroyEntity(maybe_remove_peripheral_id);
+                }
+            }
+        },
+        else => {
+            log.warn("TODO: implement derivation for {?}", .{entity_type});
+        },
+    }
 }
 
 pub fn loadPeripheral(ctx: *Context, node: xml.Node, device_id: EntityId) !void {