diff --git a/compression/JFJochCompressor.cpp b/compression/JFJochCompressor.cpp
index 1afa0177..c144abb1 100644
--- a/compression/JFJochCompressor.cpp
+++ b/compression/JFJochCompressor.cpp
@@ -37,7 +37,7 @@ JFJochBitShuffleCompressor::JFJochBitShuffleCompressor(CompressionAlgorithm in_a
 size_t JFJochBitShuffleCompressor::CompressBlock(char *dest, const char *source, size_t nelements, size_t elem_size) {
 // Assert nelements < block_size
     const char *src_ptr;
-    int64_t bshuf_ret = bitshuf_encode_block(tmp_space.data(), source, scratch, nelements, elem_size);
+    int64_t bshuf_ret = bitshuf_encode_block(tmp_space.data(), source, scratch.data(), nelements, elem_size);
     if (bshuf_ret < 0)
         throw JFJochException(JFJochExceptionCategory::Compression, "bshuf_trans_bit_elem error");
     src_ptr = tmp_space.data();
@@ -100,6 +100,8 @@ int64_t JFJochBitShuffleCompressor::Compress(void *dest, size_t dest_size, const
 
     if (tmp_space.size() < DefaultBlockSize * elem_size)
         tmp_space.resize(DefaultBlockSize * elem_size);
+    if (scratch.size() < DefaultBlockSize * elem_size)
+        scratch.resize(DefaultBlockSize * elem_size);
 
     size_t num_full_blocks = nelements / DefaultBlockSize;
     size_t reminder_size = nelements - num_full_blocks * DefaultBlockSize;
diff --git a/compression/JFJochCompressor.h b/compression/JFJochCompressor.h
index 255a49cb..30bcbcc7 100644
--- a/compression/JFJochCompressor.h
+++ b/compression/JFJochCompressor.h
@@ -17,10 +17,11 @@ class JFJochBitShuffleCompressor {
     JFJochZstdCompressor zstd_compressor;
     CompressionAlgorithm algorithm;
     std::vector<char> tmp_space;
+    std::vector<char> scratch;
 
     size_t CompressBlock(char *dest, const char * source, size_t nelements, size_t elem_size);
 public:
-    constexpr static const size_t DefaultBlockSize = 4096;
+    constexpr static const size_t DefaultBlockSize = 16384;
 
     explicit JFJochBitShuffleCompressor(CompressionAlgorithm algorithm);
 
@@ -35,8 +36,6 @@ public:
     }
     std::vector<uint8_t> Compress(const void* source, size_t nelements, size_t elem_size);
     int64_t Compress(void *dest, size_t dest_size, const void* source, size_t nelements, size_t elem_size);
-private:
-    char scratch[DefaultBlockSize * sizeof(uint64_t)];
 };
 
 template <class T> std::vector<T> bitshuffle(const std::vector<T> &input, size_t block_size) {