diff --git a/py/minimint/mist_interpolator.py b/py/minimint/mist_interpolator.py
index e515b75..8679520 100644
--- a/py/minimint/mist_interpolator.py
+++ b/py/minimint/mist_interpolator.py
@@ -63,8 +63,10 @@ def getheader(f):
 
 
 def read_grid(eep_prefix, outp_prefix):
-    fs = glob.glob(os.path.join(eep_prefix, '*EEPS', '*eep'))
-    assert (len(fs) > 0)
+    mask = os.path.join(eep_prefix, '*EEPS', '*eep')
+    fs = glob.glob(mask)
+    if len(fs) == 0:
+        raise RuntimeError(f'Failed to find eep files {mask}')
     tmpfile = utils.tail_head(fs[0], 11, 10)
     tab0 = atpy.Table().read(tmpfile, format='ascii.fast_commented_header')
     os.unlink(tmpfile)
@@ -168,12 +170,14 @@ def writer(url, pref):
         fd.close()
         if os.name == 'nt':
             fname_out1 = fname_out.replace('.txz', '.tar')
-            cmd = f'cd {pref} && 7z x {fname_out} -so > {fname_out1} && tar -xf {fname_out1}'
+            cmd = (f'cd {pref} && '
+                   f'7z x {fname_out} -so > {fname_out1} && '
+                   f'tar -xf {fname_out1}')
         else:
             cmd = f'cd {pref}; tar xfJ {fname_out}'
-            
-        #ret = subprocess.run(cmd, capture_output=True, shell=True, timeout=60)
-        ret = subprocess.run(cmd, shell=True, timeout=60)
+        print(fname_out, fname_out1)
+        ret = subprocess.run(cmd, capture_output=True, shell=True, timeout=60)
+        # ret = subprocess.run(cmd, shell=True, timeout=60)
         if ret.returncode != 0:
             raise RuntimeError('Failed to untar the files' +
                                ret.stdout.decode() + ret.stderr.decode())