diff --git a/adafruit_ticks.py b/adafruit_ticks.py
index 5585d2b..3efb0ad 100644
--- a/adafruit_ticks.py
+++ b/adafruit_ticks.py
@@ -122,7 +122,9 @@ def ticks_ms() -> int:
 
 def ticks_add(ticks: int, delta: int) -> int:
     "Add a delta to a base number of ticks, performing wraparound at 2**29ms."
-    return (ticks + delta) % _TICKS_PERIOD
+    if -_TICKS_HALFPERIOD < delta < _TICKS_HALFPERIOD:
+        return (ticks + delta) % _TICKS_PERIOD
+    raise OverflowError("ticks interval overflow")
 
 
 def ticks_diff(ticks1: int, ticks2: int) -> int: