diff --git a/applepy.py b/applepy.py
index 4fbfa37..5052474 100644
--- a/applepy.py
+++ b/applepy.py
@@ -294,9 +294,18 @@ class Cassette:
     def __init__(self, fn):
         wav = wave.open(fn, "r")
         self.raw = wav.readframes(wav.getnframes())
+        self.start_cycle = 0
+        self.start_offset = 0
+
+        for i, b in enumerate(self.raw):
+            if ord(b) > 0xA0:
+                self.start_offset = i
+                break
 
     def read_byte(self, cycle):
-        offset = cycle * 22000 / 1000000
+        if self.start_cycle == 0:
+            self.start_cycle = cycle
+        offset = self.start_offset + (cycle - self.start_cycle) * 22000 / 1000000
         return ord(self.raw[offset]) if offset < len(self.raw) else 0x80