Return non-finite floats unchanged from naturaldelta

src/humanize/time.py

@@ -5,6 +5,7 @@
 
 from __future__ import annotations
 
+import math
 from enum import Enum
 from functools import total_ordering
 
@@ -151,6 +152,14 @@ def naturaldelta(
             delta = dt.timedelta(seconds=value)
         except (ValueError, TypeError):
             return str(value)
+        except OverflowError:
+            # `int(value)` raises OverflowError for non-finite floats (inf/-inf),
+            # which, like NaN, are returned unchanged. A too-large *finite* value
+            # (whose OverflowError comes from `timedelta`) is still raised, per
+            # the documented `OverflowError` contract.
+            if not math.isfinite(value):
+                return str(value)
+            raise
 
     use_months = months
 

tests/test_time.py

@@ -138,6 +138,19 @@ def test_naturaldelta(test_input: float | dt.timedelta, expected: str) -> None:
         assert humanize.naturaldelta(-test_input) == expected
 
 
+def test_naturaldelta_non_finite() -> None:
+    """Non-finite floats are returned unchanged instead of raising (#333)."""
+    assert humanize.naturaldelta(float("nan")) == "nan"
+    assert humanize.naturaldelta(float("inf")) == "inf"
+    assert humanize.naturaldelta(float("-inf")) == "-inf"
+
+
+def test_naturaldelta_too_large_value_raises() -> None:
+    """A too-large *finite* value still raises OverflowError (unlike inf)."""
+    with pytest.raises(OverflowError):
+        humanize.naturaldelta(1e30)
+
+
 @freeze_time(FROZEN_DATE)
 @pytest.mark.parametrize(
     "test_input, expected",