diff --git a/swn/modflow/_swnmf6.py b/swn/modflow/_swnmf6.py
index 11d18de..83dd6e0 100644
--- a/swn/modflow/_swnmf6.py
+++ b/swn/modflow/_swnmf6.py
@@ -840,14 +840,14 @@ def write_package_period(
         >>> fname_01 = dir / "model_drn_01.dat"
         >>> nm.write_package_period("drn", fname_tpl, auxiliary="dlen")
         >>> print(fname_01.read_text(), end="")
-        #k  i  j  elev  cond   dlen  boundname
-         1  1  1  10.0  15.0 18.028  101
-         1  1  2  10.0  15.0  6.009  101
-         1  2  2  10.0  15.0 12.019  101
-         1  1  2  10.0  15.0 21.082  102
-         1  2  2  10.0  15.0 10.541  102
-         1  2  2  10.0  15.0 10.000  100
-         1  3  2  10.0  15.0 10.000  100
+        #k i j  elev  cond   dlen boundname
+         1 1 1  10.0  15.0 18.028 101
+         1 1 2  10.0  15.0  6.009 101
+         1 2 2  10.0  15.0 12.019 101
+         1 1 2  10.0  15.0 21.082 102
+         1 2 2  10.0  15.0 10.541 102
+         1 2 2  10.0  15.0 10.000 100
+         1 3 2  10.0  15.0 10.000 100
         >>> drn = nm.set_package_obj(
         ...    "drn", pname="swn_drn", auxmultname="dlen",
         ...    stress_period_data={0: {"filename": fname_01.name}})
diff --git a/tests/conftest.py b/tests/conftest.py
index e074ed9..dce213f 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -25,7 +25,7 @@
 from swn.compat import ignore_shapely_warnings_for_object_array
 
 
-PANDAS_MAJOR_VERSION = int(pd.__version__[0:pd.__version__.index(".")])
+PANDAS_VESRSION_TUPLE = tuple(int(x) for x in re.findall(r"\d+", pd.__version__))
 
 datadir = Path("tests") / "data"
 
diff --git a/tests/test_file.py b/tests/test_file.py
index bd7efbf..5d54f09 100644
--- a/tests/test_file.py
+++ b/tests/test_file.py
@@ -9,7 +9,7 @@
 
 import swn
 
-from .conftest import PANDAS_MAJOR_VERSION, datadir
+from .conftest import PANDAS_VESRSION_TUPLE, datadir
 
 
 # same valid network used in test_basic
@@ -150,7 +150,7 @@ def test_read_write_formatted_frame(tmp_path):
     lines = fname.read_text().splitlines()
     assert len(lines) == 7
     # check first line, space between object columns differ between versions!
-    if PANDAS_MAJOR_VERSION >= 2:
+    if (2, 0, 0) <= PANDAS_VESRSION_TUPLE <= (2, 0, 2):
         expected = "#      value1  value2  value3"
     else:
         expected = "#      value1  value2 value3"