diff --git a/contrib/spectrum_parser.py b/contrib/spectrum_parser.py
index bab6852..e54debb 100644
--- a/contrib/spectrum_parser.py
+++ b/contrib/spectrum_parser.py
@@ -25,7 +25,7 @@ def read_spectrum(path):
             next_header = f.read(256)
             while(next_header):
                 headers.append(parse_header(next_header))
-                zs.append(np.fromfile(f, dtype=np.float32, count=400))
+                zs.append(np.fromfile(f, dtype=np.float32, count=header["nchan"]))
                 next_header = f.read(256)
     return np.transpose(np.vstack(zs)), headers