diff --git a/pySTEL/libstell/boozer.py b/pySTEL/libstell/boozer.py
index ad9ec7ea..f57d8cb2 100644
--- a/pySTEL/libstell/boozer.py
+++ b/pySTEL/libstell/boozer.py
@@ -32,7 +32,8 @@ def read_boozer(self,filename):
 			Path to wout file.
 		"""
 		import numpy as np
-		boozmn_dict = self.libStell.read_boozer(filename)
+		import copy
+		boozmn_dict = copy.deepcopy(self.libStell.read_boozer(filename))
 		for key in boozmn_dict:
 			setattr(self, key, boozmn_dict[key])
 		self.mboz_b = int(max(np.squeeze(self.ixm_b)))
diff --git a/pySTEL/libstell/nescoil.py b/pySTEL/libstell/nescoil.py
index 6cf906be..725e6dac 100644
--- a/pySTEL/libstell/nescoil.py
+++ b/pySTEL/libstell/nescoil.py
@@ -30,7 +30,8 @@ class with information from a nescin file.
 		file : str
 			Path to nescin file.
 		"""
-		nescin_dict = self.libStell.read_nescoil_input(filename)
+		import copy
+		nescin_dict = copy.deepcopy(self.libStell.read_nescoil_input(filename))
 		for key in nescin_dict:
 			setattr(self, key, nescin_dict[key])
 
@@ -57,7 +58,8 @@ class with information from a nescout file.
 		file : str
 			Path to nescout file.
 		"""
-		nescout_dict = self.libStell.read_nescout(filename)
+		import copy
+		nescout_dict = copy.deepcopy(self.libStell.read_nescout(filename))
 		for key in nescout_dict:
 			setattr(self, key, nescout_dict[key])
 
diff --git a/pySTEL/libstell/vmec.py b/pySTEL/libstell/vmec.py
index 7138d708..cf8a6353 100644
--- a/pySTEL/libstell/vmec.py
+++ b/pySTEL/libstell/vmec.py
@@ -33,7 +33,8 @@ def read_wout(self,filename):
 			Path to wout file.
 		"""
 		import numpy as np
-		wout_dict = self.libStell.read_wout(filename)
+		import copy
+		wout_dict = copy.deepcopy(self.libStell.read_wout(filename))
 		for key in wout_dict:
 			setattr(self, key, wout_dict[key])
 		# (mu-nv) -> (mu+nv)