diff --git a/python/ucf/ucf.py b/python/ucf/ucf.py
index 70eeeac..d94c13c 100644
--- a/python/ucf/ucf.py
+++ b/python/ucf/ucf.py
@@ -63,7 +63,7 @@ class UCF:
 
         # Scan through file to get the basic structure (steps/sets)
         self.__timeStep      = np.zeros(self.__scanBuffSize,dtype=np.float64)
-        self.__posStep       = np.zeros(self.__scanBuffSize,dtype=np.int32)
+        self.__posStep       = np.zeros(self.__scanBuffSize,dtype=np.int64)
         self.__numSetPerStep = np.zeros(self.__scanBuffSize,dtype=np.int32)
         istep = 0;
         while self.__fileID.tell()<self.FileSize:
@@ -350,7 +350,7 @@ class UCF:
             print("%d,%d,%f,%d" % (currentMagic,self.__currentStepSize,self.__currentStepTime,self.__currentStepNumSet),file=sys.stderr) 
         # Check if magic is correct
         if currentMagic!=self.__magicStep:
-            raise ValueError("Magic mismatch: invalid step header. %d" & currentMagic);
+            raise ValueError("Magic mismatch: invalid step header. %d" % currentMagic);
     
     def __readHeaderSet(self):
       # Read and parse
@@ -425,7 +425,7 @@ class UCF:
         self.__factorTypeIDKind          = 10;
         self.__typeIDmatlabField         = 1999;
         self.__typeIDmatlabParticle      = 2999;
-        self.__scanBuffSize              = 4096;
+        self.__scanBuffSize              = 131072;
     def __resetPublicProperties(self):
         self.File         = '' # file name
         self.Type         = '' # file type