@@ -167,12 +167,23 @@ static npy_int64
 days_to_yearsdays(npy_int64 *days_)
 {
     const npy_int64 days_per_400years = (400*365 + 100 - 4 + 1);
+    const npy_int64 days_offset = (365*30 + 7);
     /* Adjust so it's relative to the year 2000 (divisible by 400) */
-    npy_int64 days = (*days_) - (365*30 + 7);
+    npy_int64 days;
     npy_int64 year;
 
+    if (*days_ < NPY_MIN_INT64 + days_offset) {
+        /* Extract 400-year cycles first to reduce magnitude */
+        days = *days_ + (days_per_400years - days_offset);
+        year = 400 * extract_unit_64(&days, days_per_400years);
+        year -= 400;
+    }
+    else {
+        days = (*days_) - days_offset;
+        year = 400 * extract_unit_64(&days, days_per_400years);
+    }
+
     /* Break down the 400 year cycle to get the year and day within the year */
-    year = 400 * extract_unit_64(&days, days_per_400years);
 
     /* Work out the year/day within the 400 year cycle */
     if (days >= 366) {
 
@@ -1265,6 +1265,16 @@ def test_arithmetic_valid_boundary(self):
         assert small * np.int64(7) == np.timedelta64(21, "s")
         assert np.int64(7) * small == np.timedelta64(21, "s")
 
+    def test_datetime64_item_int64_min_edge_case(self):
+        info = np.iinfo(np.int64)
+
+        for offset in [1, 2, 100, 1000, 10000]:
+            dt64 = np.datetime64(info.min + offset, "D")
+            result = dt64.item()
+            # expected integer value
+            assert result == info.min + offset
+            assert isinstance(result, int)
+
     def test_pyobject_roundtrip(self):
         # All datetime types should be able to roundtrip through object
         a = np.array([0, 0, 0, 0, 0, 0, 0, 0, 0,