diff --git a/.bumpversion.cfg b/.bumpversion.cfg
index e83ecab..d389d35 100644
--- a/.bumpversion.cfg
+++ b/.bumpversion.cfg
@@ -1,5 +1,5 @@
 [bumpversion]
-current_version = 1.5.7
+current_version = 1.5.8
 commit = True
 tag = True
 
diff --git a/calphy/__init__.py b/calphy/__init__.py
index 3cd0df4..cbe815a 100644
--- a/calphy/__init__.py
+++ b/calphy/__init__.py
@@ -4,7 +4,7 @@
 from calphy.alchemy import Alchemy
 from calphy.routines import MeltingTemp
 
-__version__ = "1.5.7"
+__version__ = "1.5.8"
 
 def addtest(a,b):
     return a+b
diff --git a/calphy/input.py b/calphy/input.py
index 9b4ea48..de3737f 100644
--- a/calphy/input.py
+++ b/calphy/input.py
@@ -49,7 +49,7 @@
 from ase.io import read, write
 import shutil
 
-__version__ = "1.5.7"
+__version__ = "1.5.8"
 
 
 def _check_equal(val):
@@ -812,7 +812,10 @@ def create_identifier(self):
         elif np.isscalar(self.pressure):
             ps = "%d" % (int(self.pressure))
         else:
-            ps = "%d" % (int(self.pressure[0]))
+            if isinstance(self.pressure[0], list):
+                ps = "%d" % (int(self.pressure[0][0]))
+            else:
+                ps = "%d" % (int(self.pressure[0]))
 
         if hasattr(self, "_original_lattice") and self._original_lattice:
             l = self._original_lattice
diff --git a/setup.py b/setup.py
index 258accd..d24d1a4 100644
--- a/setup.py
+++ b/setup.py
@@ -53,7 +53,7 @@
     packages=find_packages(include=['calphy', 'calphy.*']),
     test_suite='tests',
     url='https://github.com/ICAMS/calphy',
-    version='1.5.7',
+    version='1.5.8',
     zip_safe=False,
     entry_points={
         'console_scripts': [