diff --git a/plumed/io/parsers/__init__.py b/plumed/io/parsers/__init__.py
index 971ea0d..918ffb8 100644
--- a/plumed/io/parsers/__init__.py
+++ b/plumed/io/parsers/__init__.py
@@ -1,7 +1,7 @@
 
-from read_wham import read_wham
-from read_colvar import read_colvar
-from read_fes import read_fes
-from read_hills import read_hills
-from read_plumed import read_plumed
-from read_str import read_str
+from .read_wham import read_wham
+from .read_colvar import read_colvar
+from .read_fes import read_fes
+from .read_hills import read_hills
+from .read_plumed import read_plumed
+from .read_str import read_str
diff --git a/plumed/io/parsers/read_colvar.py b/plumed/io/parsers/read_colvar.py
index c9b27d8..af7528d 100644
--- a/plumed/io/parsers/read_colvar.py
+++ b/plumed/io/parsers/read_colvar.py
@@ -3,17 +3,19 @@
 import numpy as np
 import six
 
+
 def read_colvar(fname, verbose=False):
-	if verbose: print(fname)
-	f = open(fname) if isinstance(fname, six.string_types) else fname
+    if verbose:
+        print(fname)
+    f = open(fname) if isinstance(fname, six.string_types) else fname
 
-	with f:
-		line = f.readline()
-		assert line[:2] == '#!', 'Missing or incorrect header'
-		columns = line.split()[2:]
-		f.seek(0)
-		df = pd.read_csv(f, delim_whitespace=True, comment="#", skiprows=1, header=None)
+    with f:
+        line = f.readline()
+        assert line[:2] == '#!', 'Missing or incorrect header'
+        columns = line.split()[2:]
+        f.seek(0)
+        df = pd.read_csv(f, delim_whitespace=True, comment="#", skiprows=1, header=None)
 
-	df.columns = columns
-	df.time = map(np.round, df.time)
-	return df
+    df.columns = columns
+    df.time = map(np.round, df.time)
+    return df
diff --git a/plumed/io/parsers/read_fes.py b/plumed/io/parsers/read_fes.py
index a1708cd..d171dfb 100644
--- a/plumed/io/parsers/read_fes.py
+++ b/plumed/io/parsers/read_fes.py
@@ -1,10 +1,11 @@
 
 import pandas as pd
 
+
 def read_fes(fname):
-	lines = [l[1:] for l in open(fname).readlines() if l.startswith("#")]
-	columns = lines[1].split()
-	data = [map(float, l.split()) for l in lines[2:]]
-	df = pd.DataFrame(data, columns=columns)
-	df.Window = map(int, df.Window)
-	return df
+    lines = [l[1:] for l in open(fname).readlines() if l.startswith("#")]
+    columns = lines[1].split()
+    data = [map(float, l.split()) for l in lines[2:]]
+    df = pd.DataFrame(data, columns=columns)
+    df.Window = map(int, df.Window)
+    return df
diff --git a/plumed/io/parsers/read_hills.py b/plumed/io/parsers/read_hills.py
index 5e063d8..35d9019 100644
--- a/plumed/io/parsers/read_hills.py
+++ b/plumed/io/parsers/read_hills.py
@@ -1,9 +1,10 @@
 
 import pandas as pd
 
+
 def read_hills(f="HILLS"):
-	lines = open(f).readlines()
-	columns = lines[0].split()[2:]
-	data = [map(float, l.split()) for l in lines if not l.startswith("#")]
-	df = pd.DataFrame(data, columns=columns)
-	return df
+    lines = open(f).readlines()
+    columns = lines[0].split()[2:]
+    data = [map(float, l.split()) for l in lines if not l.startswith("#")]
+    df = pd.DataFrame(data, columns=columns)
+    return df
diff --git a/plumed/io/parsers/read_str.py b/plumed/io/parsers/read_str.py
index 504c60d..e78dc24 100644
--- a/plumed/io/parsers/read_str.py
+++ b/plumed/io/parsers/read_str.py
@@ -1,6 +1,7 @@
 
 import pandas as pd
 
+
 def read_str(filename):
 
     columns = ['_Gen_dist_constraint.ID',
diff --git a/plumed/io/parsers/read_wham.py b/plumed/io/parsers/read_wham.py
index 3e29dec..c51c226 100644
--- a/plumed/io/parsers/read_wham.py
+++ b/plumed/io/parsers/read_wham.py
@@ -1,8 +1,9 @@
 
 import pandas as pd
 
+
 def read_wham(fname):
-	df = pd.read_csv(fname, sep="\t", comment="#", header=None)
-	columns = "Coor		Free	FreeErr		Prob		ProbErr".split()
-	df.columns = columns
-	return df
+    df = pd.read_csv(fname, sep="\t", comment="#", header=None)
+    columns = "Coor		Free	FreeErr		Prob		ProbErr".split()
+    df.columns = columns
+    return df