diff --git a/heuristics.py b/heuristics.py
new file mode 100644
index 0000000..4f29b44
--- /dev/null
+++ b/heuristics.py
@@ -0,0 +1,40 @@
+def try_scene(f):
+    f.seek(0)
+    while True:
+        command = f.read(8)
+        if len(command) == 0:
+            return False
+        if command[2:4] != b'\x00\x00':
+            return False
+        if command[0] > 0x1e:
+            return False
+        if command[4] != 0x02 and command[4] != 0x00:
+            if command[0] not in (0x05, 0x10, 0x11, 0x12):
+                return False
+        if command == b'\x14\x00\x00\x00\x00\x00\x00\x00':
+            return True
+
+def try_room(f):
+    # note: doesn't detect syotes_room_0 because it's missing a header
+    f.seek(0)
+    while True:
+        command = f.read(8)
+        if len(command) == 0:
+            return False
+        if command[2:4] != b'\x00\x00':
+            return False
+        if command[0] > 0x1e:
+            return False
+        if command[4] != 0x03 and command[4] != 0x00:
+            if command[0] not in (0x05, 0x10, 0x11, 0x12):
+                return False
+        if command == b'\x14\x00\x00\x00\x00\x00\x00\x00':
+            return True
+
+def detect_format(f, fn=None):
+    if try_scene(f):
+        return 'scene'
+    if try_room(f):
+        return 'room'
+
+    return None
diff --git a/z64dump.py b/z64dump.py
index af201a8..2130674 100755
--- a/z64dump.py
+++ b/z64dump.py
@@ -7,6 +7,7 @@ from io import BytesIO
 from hashlib import sha1
 
 from util import *
+from heuristics import *
 import n64
 import Yaz0
 
@@ -15,6 +16,12 @@ lament = lambda *args, **kwargs: print(*args, file=sys.stderr, **kwargs)
 # assume first entry is makerom (0x1060), and second entry begins from makerom
 dma_sig = b"\x00\x00\x00\x00\x00\x00\x10\x60\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x10\x60"
 
+def dump_wrap(data, fn, size):
+    kind = detect_format(BytesIO(data), fn)
+    if kind is not None:
+        fn += '.' + kind
+    dump_as(data, fn, size)
+
 def z_dump_file(f, i=0, name=None):
     vs = R4(f.read(4)) # virtual start
     ve = R4(f.read(4)) # virtual end
@@ -41,20 +48,20 @@ def z_dump_file(f, i=0, name=None):
         pe = ps + size
         f.seek(ps)
         data = f.read(pe - ps)
-        dump_as(data, fn, size)
+        dump_wrap(data, fn, size)
     else:
         #lament('file is compressed')
         f.seek(ps)
         compressed = f.read(pe - ps)
         if compressed[:4] == b'Yaz0':
             data = Yaz0.decode(compressed)
-            dump_as(data, fn, size)
+            dump_wrap(data, fn, size)
         else:
             lament('unknown compression; skipping:', fn)
             lament(compressed[:4])
 
     f.seek(here)
-    return True, fn, vs, ve, ps, pe
+    return True
 
 def z_find_dma(f):
     while True: