diff --git a/autotest/regression/test_mf6.py b/autotest/regression/test_mf6.py
index 2f8b1a2418..6b8b8d207e 100644
--- a/autotest/regression/test_mf6.py
+++ b/autotest/regression/test_mf6.py
@@ -948,9 +948,14 @@ def test_np002(function_tmpdir, example_data_path):
     oc_package.printrecord.set_data([("HEAD", "ALL"), ("BUDGET", "ALL")], 1)
 
     sto_package = ModflowGwfsto(
-        model, save_flows=True, iconvert=1, ss=0.000001, sy=0.15
+        model, save_flows=True, iconvert=0, ss=0.000001, sy=None, pname="sto_t"
     )
+    sto_package.check()
 
+    model.remove_package("sto_t")
+    sto_package = ModflowGwfsto(
+        model, save_flows=True, iconvert=1, ss=0.000001, sy=0.15
+    )
     hfb_package = ModflowGwfhfb(
         model,
         print_input=True,
diff --git a/flopy/pakbase.py b/flopy/pakbase.py
index 11aee0f5a6..432381820c 100644
--- a/flopy/pakbase.py
+++ b/flopy/pakbase.py
@@ -413,6 +413,15 @@ def _check_storage(self, chk, storage_coeff):
                     skip_sy_check = True
             else:
                 iconvert = self.iconvert.array
+                inds = np.array(
+                    [
+                        True if l > 0 or l < 0 else False
+                        for l in iconvert.flatten()
+                    ]
+                )
+                if not inds.any():
+                    skip_sy_check = True
+
                 for ishape in np.ndindex(active.shape):
                     if active[ishape]:
                         active[ishape] = (