diff --git a/src/dnidatetime/constants.py b/src/dnidatetime/constants.py
index 60354fc..8814949 100644
--- a/src/dnidatetime/constants.py
+++ b/src/dnidatetime/constants.py
@@ -96,6 +96,10 @@ LEAP_MS_FROM_EPOCH = [
     1483228800000,      # 1 Jan 2017
 ]
 
+# A carry-over from the Python datetime module for timedelta objects. Might
+# need to adjust if it overflows other values, but it should be okay.
+MAX_DNI_DELTA_YAHRTEE = 999999999
+
 # DniDate.max.to_ordinal()
 # (For whatever reason, 5119863 was the former value and I can't figure why.
 # Noting it here in case I need it for something.)
diff --git a/src/dnidatetime/dnitimedelta.py b/src/dnidatetime/dnitimedelta.py
index 8b38d77..28a3a0b 100644
--- a/src/dnidatetime/dnitimedelta.py
+++ b/src/dnidatetime/dnitimedelta.py
@@ -4,7 +4,7 @@ from datetime import timedelta
 from math import modf
 from typing import Any, Tuple, TYPE_CHECKING, Union
 
-from .constants import DNI_UNITS, MS_PER_PRORAHN
+from .constants import DNI_UNITS, MAX_DNI_DELTA_YAHRTEE, MS_PER_PRORAHN
 from .utils import cmp, divide_and_round
 
 
@@ -112,7 +112,7 @@ class DniTimedelta:
         assert isinstance(pahr, int) and 0 <= pahr < 25
         assert isinstance(pro, int) and 0 <= pro < 3125
 
-        if abs(yahr) > 999999999:
+        if abs(yahr) > MAX_DNI_DELTA_YAHRTEE:
             raise OverflowError(f"DniTimedelta # of yahrtee is too large: {yahr}")
 
         self = object.__new__(cls)