diff --git a/inc/Kcounter.h b/inc/Kcounter.h
index f87cef3..73ecc95 100644
--- a/inc/Kcounter.h
+++ b/inc/Kcounter.h
@@ -13,13 +13,13 @@ class Kcounter
     public:
         Kcounter( const int k );
         ~Kcounter();
-        void insert( char* kmer, int count );
+        void insert( char* kmer, count_dtype count );
         bool contains( char* kmer );
         void clear();
         uint64_t size();
         void remove( char* kmer );
         void add_seq( char* seq, uint32_t length );
-        int get( char* kmer );
+        count_dtype get( char* kmer );
         int get_k() { return m_k; }
         Kcontainer* get_kc() { return kc; }
         void parallel_add_init(int threads) {
diff --git a/inc/UContainer.h b/inc/UContainer.h
index 9233384..6857b8e 100644
--- a/inc/UContainer.h
+++ b/inc/UContainer.h
@@ -15,7 +15,7 @@ typedef struct {
 #if KDICT
     py::handle* objs;
 #elif KCOUNTER
-    int* counts;
+    count_dtype* counts;
 #endif
     uint16_t size;
 } UC;
diff --git a/inc/globals.h b/inc/globals.h
index 5902462..dc56e25 100644
--- a/inc/globals.h
+++ b/inc/globals.h
@@ -1,7 +1,11 @@
 #pragma once
 
+#include <stdint.h>
+
 #define CAPACITY    4096
 #define NHASHES     12
 #define HASHSIZE    512     // HASHSIZE % 32 must be 0
 
 
+typedef uint16_t count_dtype;
+#define MAXCOUNT    UINT16_MAX
diff --git a/kcollections/src/Kcounter.cc b/kcollections/src/Kcounter.cc
index 3603f6e..686c232 100644
--- a/kcollections/src/Kcounter.cc
+++ b/kcollections/src/Kcounter.cc
@@ -18,13 +18,13 @@ void Kcounter::clear()
     kc = create_kcontainer( m_k );
 }
 
-void Kcounter::insert( char* kmer, int count )
+void Kcounter::insert( char* kmer, count_dtype count )
 {
     CHECK_KMER_LENGTH( kmer, m_k, "Kcounter" );
     kcontainer_add( kc, kmer, count );
 }
 
-int Kcounter::get( char* kmer )
+count_dtype Kcounter::get( char* kmer )
 {
     CHECK_KMER_LENGTH( kmer, m_k, "Kcounter" );
     return kcontainer_get( kc, kmer );
diff --git a/kcollections/src/UContainer.cc b/kcollections/src/UContainer.cc
index 968c18c..065d086 100644
--- a/kcollections/src/UContainer.cc
+++ b/kcollections/src/UContainer.cc
@@ -38,7 +38,7 @@ void uc_insert( UC* uc, uint8_t* bseq, int k, int depth, int idx, int count )
 #if KDICT
         uc->objs = ( py::handle* ) calloc( len , sizeof( py::handle ) );
 #elif KCOUNTER
-        uc->counts = ( int* ) calloc( len, sizeof( int ) );
+        uc->counts = ( count_dtype* ) calloc( len, sizeof(count_dtype) );
 #endif
     }
     else
@@ -53,9 +53,9 @@ void uc_insert( UC* uc, uint8_t* bseq, int k, int depth, int idx, int count )
                 ( uc->size + 1 ) * sizeof( py::handle )
                 );
 #elif KCOUNTER
-        uc->counts = ( int* ) realloc(
+        uc->counts = ( count_dtype* ) realloc(
                 uc->counts,
-                ( uc->size + 1 ) * sizeof( int )
+                ( uc->size + 1 ) * sizeof(count_dtype)
                 );
 #endif
     }
@@ -80,7 +80,7 @@ void uc_insert( UC* uc, uint8_t* bseq, int k, int depth, int idx, int count )
                     bytes_to_move
                     );
 #elif KCOUNTER
-            bytes_to_move = ( uc->size - idx ) * sizeof( int );
+            bytes_to_move = ( uc->size - idx ) * sizeof(count_dtype);
             std::memmove(
                     &uc->counts[ idx + 1 ],
                     &uc->counts[ idx ],
@@ -90,10 +90,12 @@ void uc_insert( UC* uc, uint8_t* bseq, int k, int depth, int idx, int count )
         }
 
 #if KDICT
-        std::memcpy( &uc->objs[ idx ], obj, sizeof( py::handle ) );
-        uc->objs[ idx ].inc_ref();
+        std::memcpy(&uc->objs[idx], obj, sizeof(py::handle));
+        uc->objs[idx].inc_ref();
 #elif KCOUNTER
-        std::memcpy( &uc->counts[ idx ], &count, sizeof( int ) );
+        if(uc->counts[idx] < MAXCOUNT) {
+            std::memcpy(&uc->counts[idx], &count, sizeof(count_dtype));
+        }
 #endif
         std::memcpy( &uc->suffixes[ suffix_idx ], bseq, len );
         uc->size++;
@@ -138,7 +140,7 @@ void uc_remove( UC* uc, int bk, int idx )
             bytes_to_move
             );
 #elif KCOUNTER
-    bytes_to_move = ( uc->size - ( idx + 1 ) ) * sizeof( int );
+    bytes_to_move = ( uc->size - ( idx + 1 ) ) * sizeof( count_dtype );
     std::memmove(
             &uc->counts[ idx ],
             &uc->counts[ idx + 1 ],
diff --git a/kcollections/src/Vertex.cc b/kcollections/src/Vertex.cc
index bba0a69..5be0a1b 100644
--- a/kcollections/src/Vertex.cc
+++ b/kcollections/src/Vertex.cc
@@ -139,7 +139,7 @@ void burst_uc( Vertex* v, int k, int depth )
 #if KDICT
     py::handle* objs = v->uc.objs;
 #elif KCOUNTER
-    int* counts = v->uc.counts;
+    count_dtype* counts = v->uc.counts;
 #endif
     int idx;
     for( int i = 0; i < v->uc.size; i++ )
@@ -229,11 +229,13 @@ void vertex_insert( Vertex* v, uint8_t* bseq, int k, int depth, int count )
                 );
         v->uc.objs[ uc_idx ].inc_ref();
 #elif KCOUNTER
-        std::memcpy(
-                &v->uc.counts[ uc_idx ],
-                &count,
-                sizeof( int )
-                );
+        if(v->uc.counts[uc_idx] < MAXCOUNT) {
+            std::memcpy(
+                    &v->uc.counts[ uc_idx ],
+                    &count,
+                    sizeof(count_dtype)
+                    );
+        }
 #endif
         return;
     }
diff --git a/scripts/counter.bft.parallel.fast.py b/scripts/counter.bft.parallel.fast.py
new file mode 100644
index 0000000..5711a9e
--- /dev/null
+++ b/scripts/counter.bft.parallel.fast.py
@@ -0,0 +1,76 @@
+#!/usr/bin/env python
+
+import kcollections, sys, time
+from tqdm import tqdm
+
+k = int(sys.argv[1])
+threads = int(sys.argv[2])
+ks = kcollections.Kcounter(k)
+ks.parallel_add_init(threads)
+
+seqs = []
+seq = ''
+c = 0
+
+start_time = time.time()
+
+with(open(sys.argv[3], 'r')) as fh:
+    for line in fh:
+        if line[0] == '>':
+            if len(seq) > 0:
+                #seqs.append(seq)
+                tstart_time = time.time()
+                ks.parallel_add_seq(seq, len(seq))
+                telapsed_time = time.time() - tstart_time
+                print c, '\tadded seq of len', len(seq), telapsed_time
+                sys.stdout.flush()
+            c += 1
+            seq = ''
+        else:
+            seq += line.strip()
+    if len(seq) > 0:
+        #seqs.append(seq)
+        tstart_time = time.time()
+        ks.parallel_add_seq(seq, len(seq))
+        telapsed_time = time.time() - tstart_time
+        print c, '\tadded seq of len', len(seq), telapsed_time
+
+ks.parallel_add_join()
+
+elapsed_time = time.time() - start_time
+print 'elapsed time:', elapsed_time
+#print 'read', len(seqs), 'seqs, adding to ks...'
+
+#for seq in seqs:
+#    print '\tadding seq...'
+#    sys.stdout.flush()
+#    ks.parallel_add_seq(seq, len(seq))
+
+print len(ks), 'kmers'
+print 'done!'
+print 'checking correctness'
+
+for kmer, count in ks.iteritems():
+    print kmer, count
+
+c = 0
+if len(sys.argv) > 4:
+    with open(sys.argv[3], 'r') as fh:
+        seq = ''
+        for line in fh:
+            if line[0] == '>':
+                if len(seq) > 0:
+                    for i in range(len(seq) - k + 1):
+                        kmer = seq[i : i + k]
+                        assert kmer in ks, "not find: " + kmer
+                        c += 1
+                seq = ''
+            else:
+                seq += line.strip()
+    for i in range(len(seq) - k + 1):
+        kmer = seq[i : i + k]
+        assert kmer in ks, "not find: " + kmer
+        c += 1
+print 'checked', c, 'kmers'
+
+del ks
diff --git a/setup.py b/setup.py
index 12be87a..40ae7bf 100755
--- a/setup.py
+++ b/setup.py
@@ -5,7 +5,7 @@
 from setuptools import setup, Extension, find_packages
 from setuptools.command.build_ext import build_ext
 
-__version__ = '0.0.9'
+__version__ = '0.1'
 
 class CMakeExtension(Extension):
     def __init__(self, name, sourcedir=''):