diff --git a/pyerrors/input/openQCD.py b/pyerrors/input/openQCD.py
index f11fb4e6..08bb0223 100644
--- a/pyerrors/input/openQCD.py
+++ b/pyerrors/input/openQCD.py
@@ -39,13 +39,15 @@ def read_rwms(path, prefix, version='2.0', names=None, **kwargs):
 
     if not ls:
         raise Exception('Error, directory not found')
-
-    # Exclude files with different names
-    for exc in ls:
-        if not fnmatch.fnmatch(exc, prefix + '*' + postfix + '.dat'):
-            ls = list(set(ls) - set([exc]))
-    if len(ls) > 1:
-        ls.sort(key=lambda x: int(re.findall(r'\d+', x[len(prefix):])[0]))
+    if 'files' in kwargs:
+        ls = kwargs.get('files')
+    else:
+        # Exclude files with different names
+        for exc in ls:
+            if not fnmatch.fnmatch(exc, prefix + '*' + postfix + '.dat'):
+                ls = list(set(ls) - set([exc]))
+        if len(ls) > 1:
+            ls.sort(key=lambda x: int(re.findall(r'\d+', x[len(prefix):])[0]))
     replica = len(ls)
 
     if 'r_start' in kwargs:
diff --git a/pyerrors/input/utils.py b/pyerrors/input/utils.py
new file mode 100644
index 00000000..f4264587
--- /dev/null
+++ b/pyerrors/input/utils.py
@@ -0,0 +1,15 @@
+import fnmatch
+
+def check_missing(idl,che):
+    missing = []
+    for ind in che:
+            if not ind in idl:
+                missing.append(ind)
+    if(len(missing) == 0):
+        print("There are no measurements missing.")
+    else:
+        print(len(missing),"measurements missing")
+        miss_str = str(missing[0])
+        for i in missing[1:]:
+            miss_str += ","+str(i)
+        print(miss_str)