diff --git a/strax/processing/general.py b/strax/processing/general.py
index f7e4735e..b3b63b9e 100644
--- a/strax/processing/general.py
+++ b/strax/processing/general.py
@@ -82,6 +82,8 @@ def _overload_endtime(x):
 @numba.jit(nopython=True, nogil=True, cache=True)
 def diff(data):
     """Return time differences between items in data."""
+    if len(data) == 0:
+        return np.zeros(0, dtype=data.dtype["time"])
     results = np.zeros(len(data) - 1, dtype=data.dtype["time"])
     max_endtime = strax.endtime(data[0])
     for i, (time, endtime) in enumerate(zip(data["time"][1:], strax.endtime(data)[:-1])):