diff --git a/unusedsymbols.py b/unusedsymbols.py
new file mode 100755
index 0000000..ea250e4
--- /dev/null
+++ b/unusedsymbols.py
@@ -0,0 +1,259 @@
+#!/usr/bin/env python3
+# vim:set tabstop=4 shiftwidth=4 expandtab smarttab
+
+from sys import argv, exit, stderr
+from struct import unpack, calcsize
+from enum import Enum
+
+class nodetype(Enum):
+    REPT = 0
+    FILE = 1
+    MACRO = 2
+
+class symtype(Enum):
+    LOCAL = 0
+    IMPORT = 1
+    EXPORT = 2
+
+class sectype(Enum):
+    WRAM0 = 0
+    VRAM = 1
+    ROMX = 2
+    ROM0 = 3
+    HRAM = 4
+    WRAMX = 5
+    SRAM = 6
+    OAM = 7
+
+class patchtype(Enum):
+    BYTE = 0
+    WORD = 1
+    LONG = 2
+    JR = 3
+
+class asserttype(Enum):
+    WARN = 0
+    ERROR = 1
+    FAIL = 2
+
+def unpack_file(fmt, file):
+    size = calcsize(fmt)
+    return unpack(fmt, file.read(size))
+
+def read_string(file):
+    buf = bytearray()
+    while True:
+        b = file.read(1)
+        if b is None or b == b'\0':
+            return buf.decode()
+        else:
+            buf += b
+
+def parse_object(filename):
+    file = open(filename, "rb")
+
+    obj = {
+        "nodes": [],
+        "symbols": [],
+        "sections": [],
+        "assertions": [],
+    }
+
+    magic = unpack_file("4s", file)[0]
+    if magic == b'RGB6':
+        obj_ver = 6
+    elif magic == b'RGB9':
+        obj_ver = 10 + unpack_file("<I", file)[0]
+    else:
+        print("Error: File '%s' is of an unknown format." % filename, file=stderr)
+        return None
+
+    if obj_ver not in [6, 10, 11, 13, 14, 16]:
+        print("Error: File '%s' is of an unknown format: %d" % (filename, obj_ver), file=stderr)
+        return None
+
+    obj["version"] = obj_ver
+
+    num_symbols, num_sections = unpack_file("<II", file)
+
+    num_nodes = 0
+    if obj_ver >= 16:
+        num_nodes = unpack_file("<I", file)[0]
+
+    for x in range(num_nodes):
+        node = {}
+
+        node["parent_id"], node["parent_line"] = unpack_file("<II", file)
+        node["type"] = nodetype(unpack_file("<B", file)[0])
+        if node["type"] != nodetype.REPT:
+            node["name"] = read_string(file)
+        else:
+            depth = unpack_file("<I", file)[0]
+            node["depth"] = [unpack_file("<I", file) for x in range(depth)]
+        obj["nodes"].append(node)
+
+    for x in range(num_symbols):
+        symbol = {}
+
+        symbol["name"] = read_string(file)
+        symbol["type"] = symtype(unpack_file("<B", file)[0])
+        if symbol["type"] != symtype.IMPORT:
+            if obj_ver >= 16:
+                node = unpack_file("<I", file)[0]
+                symbol["node"] = node
+            else:
+                symbol["filename"] = read_string(file)
+            symbol["line_num"], symbol["section"], symbol["value"] = unpack_file("<III", file)
+
+        obj["symbols"].append(symbol)
+
+    for x in range(num_sections):
+        section = {}
+
+        section["name"] = read_string(file)
+        size, type, section["org"], section["bank"] = unpack_file("<IBII", file)
+        section["type"] = sectype(type)
+
+        if obj_ver >= 14:
+            section["align"], section["offset"] = unpack_file("<BI", file)
+        else:
+            section["align"] = unpack_file("<I", file)[0]
+
+        if section["type"] == sectype.ROMX or section["type"] == sectype.ROM0:
+            section["data"] = file.read(size)
+
+            section["patches"] = []
+            num_patches = unpack_file("<I", file)[0]
+            for x in range(num_patches):
+                patch = {}
+
+                if obj_ver >= 16:
+                    node = unpack_file("<I", file)[0]
+                    patch["node"] = node
+                else:
+                    patch["filename"] = read_string(file)
+                if obj_ver < 11 or obj_ver >= 16:
+                    patch["line"] = unpack_file("<I", file)[0]
+                patch["offset"] = unpack_file("<I", file)[0]
+                if obj_ver >= 14:
+                    patch["pcsectionid"], patch["pcoffset"] = unpack_file("<II", file)
+                type, rpn_size = unpack_file("<BI", file)
+                patch["type"] = patchtype(type)
+                patch["rpn"] = file.read(rpn_size)
+
+                section["patches"].append(patch)
+
+        obj["sections"].append(section)
+
+    num_assertions = 0
+    if obj_ver >= 13:
+        num_assertions = unpack_file("<I", file)[0]
+
+    for x in range(num_assertions):
+        assertion = {}
+
+        if obj_ver >= 16:
+            node = unpack_file("<I", file)[0]
+            assertion["node"] = node
+            assertion["line"] = unpack_file("<I", file)[0]
+        else:
+            assertion["filename"] = read_string(file)
+        assertion["offset"] = unpack_file("<I", file)[0]
+        if obj_ver >= 14:
+            assertion["section"], assertion["pcoffset"] = unpack_file("<II")
+        type, rpn_size = unpack_file("<BI", file)
+        assertion["type"] = asserttype(type)
+        assertion["rpn"] = file.read(rpn_size)
+        assertion["message"] = read_string(file)
+
+        obj["assertions"].append(assertion)
+
+    return obj
+
+
+if len(argv) <= 1:
+    print("Usage: %s [-D] <objects.o...>" % argv[0], file=stderr)
+    exit(1)
+
+argi = 1
+
+just_dump = False
+if argv[argi] == "-D":
+    just_dump = True
+    argi += 1
+if argv[argi] == "--":
+    argi += 1
+
+globalsyms = {}
+
+for filename in argv[argi:]:
+    print(filename, file=stderr)
+
+    obj = parse_object(filename)
+    if obj is None:
+        exit(1)
+
+    if just_dump:
+        for symbol in obj["symbols"]:
+            print(symbol["name"])
+        continue
+
+    localsyms = {}
+
+    imports = 0
+    exports = 0
+    for symbol in obj["symbols"]:
+        if symbol["type"] == symtype.LOCAL:
+            if symbol["name"] not in localsyms:
+                localsyms[symbol["name"]] = 0
+        elif symbol["type"] == symtype.IMPORT:
+            imports += 1
+            if symbol["name"] not in globalsyms:
+                globalsyms[symbol["name"]] = 0
+        elif symbol["type"] == symtype.EXPORT:
+            exports += 1
+            if symbol["name"] not in globalsyms:
+                globalsyms[symbol["name"]] = 0
+
+    print("Locals:", len(localsyms), file=stderr)
+    print("Imports:", imports, file=stderr)
+    print("Exports:", exports, file=stderr)
+
+    def parse_rpn(rpn):
+        pos = 0
+        while pos < len(rpn):
+            if rpn[pos] == 0x51:
+                pos += 1
+                while rpn[pos] != 0:
+                    pos += 1
+                pos += 1
+            elif rpn[pos] == 0x80:
+                pos += 5
+            elif rpn[pos] == 0x50 or rpn[pos] == 0x81:
+                symbol_id = unpack("<I", rpn[pos + 1:pos + 5])[0]
+                if symbol_id != 0xffffffff:
+                    symbol = obj["symbols"][symbol_id]
+                    if symbol["type"] == symtype.LOCAL:
+                        localsyms[symbol["name"]] += 1
+                    else:
+                        globalsyms[symbol["name"]] += 1
+                pos += 5
+            else:
+                pos += 1
+
+    for section in obj["sections"]:
+        if section["type"] == sectype.ROMX or section["type"] == sectype.ROM0:
+            for patch in section["patches"]:
+                parse_rpn(patch["rpn"])
+    for assertion in obj["assertions"]:
+        parse_rpn(assertion["rpn"])
+
+    print(file=stderr)
+
+if just_dump:
+    exit()
+
+print("Unreferenced globals:", file=stderr)
+for symbol in globalsyms:
+    if globalsyms[symbol] == 0:
+        print(symbol)