diff --git a/pandas/_libs/tslibs/conversion.pyx b/pandas/_libs/tslibs/conversion.pyx
index 536cb63cc6119..56280d55e479d 100644
--- a/pandas/_libs/tslibs/conversion.pyx
+++ b/pandas/_libs/tslibs/conversion.pyx
@@ -294,9 +294,8 @@ def ensure_timedelta64ns(arr: ndarray, copy: bool=True):
         else:
             bad_val = tdmax
 
-        raise OutOfBoundsTimedelta(
-            f"Out of bounds for nanosecond {arr.dtype.name} {bad_val}"
-        )
+        msg = f"Out of bounds for nanosecond {arr.dtype.name} {str(bad_val)}"
+        raise OutOfBoundsTimedelta(msg)
 
     return dt64_result.view(TD64NS_DTYPE)