diff --git a/src/core/codestream/ojph_codeblock_fun.cpp b/src/core/codestream/ojph_codeblock_fun.cpp
index 08d8d73..565744d 100644
--- a/src/core/codestream/ojph_codeblock_fun.cpp
+++ b/src/core/codestream/ojph_codeblock_fun.cpp
@@ -158,6 +158,8 @@ namespace ojph {
         tx_from_cb64 = NULL;
       }
       encode_cb64 = ojph_encode_codeblock64;
+      bool result = initialize_block_encoder_tables();
+      assert(result); ojph_unused(result);      
 
   #ifndef OJPH_DISABLE_SIMD
 
diff --git a/src/core/coding/ojph_block_decoder32.cpp b/src/core/coding/ojph_block_decoder32.cpp
index f54c77e..daf2312 100644
--- a/src/core/coding/ojph_block_decoder32.cpp
+++ b/src/core/coding/ojph_block_decoder32.cpp
@@ -578,7 +578,7 @@ namespace ojph {
     /** @brief State structure for reading and unstuffing of forward-growing 
      *         bitstreams; these are: MagSgn and SPP bitstreams
      */
-    struct frwd_struct {
+    struct frwd_struct32 {
       const ui8* data;  //!<pointer to bitstream
       ui64 tmp;         //!<temporary buffer of read data
       ui32 bits;        //!<number of bits stored in tmp
@@ -601,12 +601,12 @@ namespace ojph {
      *  Reading can go beyond the end of buffer by up to 3 bytes.
      *
      *  @tparam       X is the value fed in when the bitstream is exhausted
-     *  @param  [in]  msp is a pointer to frwd_struct structure
+     *  @param  [in]  msp is a pointer to frwd_struct32 structure
      *
      */ 
     template<int X>
     static inline 
-    void frwd_read(frwd_struct *msp)
+    void frwd_read(frwd_struct32 *msp)
     {
       assert(msp->bits <= 32); // assert that there is a space for 32 bits
 
@@ -653,17 +653,17 @@ namespace ojph {
     }
 
     //************************************************************************/
-    /** @brief Initialize frwd_struct struct and reads some bytes
+    /** @brief Initialize frwd_struct32 struct and reads some bytes
      *  
      *  @tparam      X is the value fed in when the bitstream is exhausted.
      *               See frwd_read regarding the template
-     *  @param [in]  msp is a pointer to frwd_struct
+     *  @param [in]  msp is a pointer to frwd_struct32
      *  @param [in]  data is a pointer to the start of data
      *  @param [in]  size is the number of byte in the bitstream
      */
     template<int X>
     static inline
-    void frwd_init(frwd_struct *msp, const ui8* data, int size)
+    void frwd_init(frwd_struct32 *msp, const ui8* data, int size)
     {
       msp->data = data;
       msp->tmp = 0;
@@ -689,13 +689,13 @@ namespace ojph {
     }
 
     //************************************************************************/
-    /** @brief Consume num_bits bits from the bitstream of frwd_struct
+    /** @brief Consume num_bits bits from the bitstream of frwd_struct32
      *
-     *  @param [in]  msp is a pointer to frwd_struct
+     *  @param [in]  msp is a pointer to frwd_struct32
      *  @param [in]  num_bits is the number of bit to consume
      */
     static inline 
-    void frwd_advance(frwd_struct *msp, ui32 num_bits)
+    void frwd_advance(frwd_struct32 *msp, ui32 num_bits)
     {
       assert(num_bits <= msp->bits);
       msp->tmp >>= num_bits;  // consume num_bits
@@ -703,15 +703,15 @@ namespace ojph {
     }
 
     //************************************************************************/
-    /** @brief Fetches 32 bits from the frwd_struct bitstream
+    /** @brief Fetches 32 bits from the frwd_struct32 bitstream
      *
      *  @tparam      X is the value fed in when the bitstream is exhausted.
      *               See frwd_read regarding the template
-     *  @param [in]  msp is a pointer to frwd_struct
+     *  @param [in]  msp is a pointer to frwd_struct32
      */
     template<int X>
     static inline 
-    ui32 frwd_fetch(frwd_struct *msp)
+    ui32 frwd_fetch(frwd_struct32 *msp)
     {
       if (msp->bits < 32)
       {
@@ -1099,7 +1099,7 @@ namespace ojph {
         const int v_n_size = 512 + 4;
         ui32 v_n_scratch[v_n_size] = {0};  // 2+ kB
 
-        frwd_struct magsgn;
+        frwd_struct32 magsgn;
         frwd_init<0xFF>(&magsgn, coded_data, lcup - scup);
 
         ui16 *sp = scratch;
@@ -1368,7 +1368,7 @@ namespace ojph {
           // We add an extra 8 entries, just in case we need more
           ui16 prev_row_sig[256 + 8] = {0}; // 528 Bytes
 
-          frwd_struct sigprop;
+          frwd_struct32 sigprop;
           frwd_init<0>(&sigprop, coded_data + lengths1, (int)lengths2);
 
           for (ui32 y = 0; y < height; y += 4)
diff --git a/src/core/coding/ojph_block_decoder64.cpp b/src/core/coding/ojph_block_decoder64.cpp
index 8801735..bce5b9e 100644
--- a/src/core/coding/ojph_block_decoder64.cpp
+++ b/src/core/coding/ojph_block_decoder64.cpp
@@ -530,7 +530,7 @@ namespace ojph {
     /** @brief State structure for reading and unstuffing of forward-growing 
      *         bitstreams; these are: MagSgn and SPP bitstreams
      */
-    struct frwd_struct {
+    struct frwd_struct64 {
       const ui8* data;  //!<pointer to bitstream
       ui64 tmp;         //!<temporary buffer of read data
       ui32 bits;        //!<number of bits stored in tmp
@@ -553,12 +553,12 @@ namespace ojph {
      *  Reading can go beyond the end of buffer by up to 3 bytes.
      *
      *  @tparam       X is the value fed in when the bitstream is exhausted
-     *  @param  [in]  msp is a pointer to frwd_struct structure
+     *  @param  [in]  msp is a pointer to frwd_struct64 structure
      *
      */ 
     template<int X>
     static inline 
-    void frwd_read(frwd_struct *msp)
+    void frwd_read(frwd_struct64 *msp)
     {
       assert(msp->bits <= 32); // assert that there is a space for 32 bits
 
@@ -617,12 +617,12 @@ namespace ojph {
      *  MSB of the next byte is set 0 and must be ignored during decoding.
      *
      *  @tparam       X is the value fed in when the bitstream is exhausted
-     *  @param  [in]  msp is a pointer to frwd_struct structure
+     *  @param  [in]  msp is a pointer to frwd_struct64 structure
      *
      */ 
     template<ui8 X>
     static inline 
-    void frwd_read8(frwd_struct *msp)
+    void frwd_read8(frwd_struct64 *msp)
     {
       ui8 val = X;
       if (msp->size > 0) {
@@ -640,17 +640,17 @@ namespace ojph {
     }
 
     //************************************************************************/
-    /** @brief Initialize frwd_struct struct and reads some bytes
+    /** @brief Initialize frwd_struct64 struct and reads some bytes
      *  
      *  @tparam      X is the value fed in when the bitstream is exhausted.
      *               See frwd_read regarding the template
-     *  @param [in]  msp is a pointer to frwd_struct
+     *  @param [in]  msp is a pointer to frwd_struct64
      *  @param [in]  data is a pointer to the start of data
      *  @param [in]  size is the number of byte in the bitstream
      */
     template<int X>
     static inline
-    void frwd_init(frwd_struct *msp, const ui8* data, int size)
+    void frwd_init(frwd_struct64 *msp, const ui8* data, int size)
     {
       msp->data = data;
       msp->tmp = 0;
@@ -676,17 +676,17 @@ namespace ojph {
     }
 
     //************************************************************************/
-    /** @brief Initialize frwd_struct struct and reads some bytes
+    /** @brief Initialize frwd_struct64 struct and reads some bytes
      *  
      *  @tparam      X is the value fed in when the bitstream is exhausted.
      *               See frwd_read regarding the template
-     *  @param [in]  msp is a pointer to frwd_struct
+     *  @param [in]  msp is a pointer to frwd_struct64
      *  @param [in]  data is a pointer to the start of data
      *  @param [in]  size is the number of byte in the bitstream
      */
     template<ui8 X>
     static inline
-    void frwd_init8(frwd_struct *msp, const ui8* data, int size)
+    void frwd_init8(frwd_struct64 *msp, const ui8* data, int size)
     {
       msp->data = data;
       msp->tmp = 0;
@@ -697,13 +697,13 @@ namespace ojph {
     }
 
     //************************************************************************/
-    /** @brief Consume num_bits bits from the bitstream of frwd_struct
+    /** @brief Consume num_bits bits from the bitstream of frwd_struct64
      *
-     *  @param [in]  msp is a pointer to frwd_struct
+     *  @param [in]  msp is a pointer to frwd_struct64
      *  @param [in]  num_bits is the number of bit to consume
      */
     static inline 
-    void frwd_advance(frwd_struct *msp, ui32 num_bits)
+    void frwd_advance(frwd_struct64 *msp, ui32 num_bits)
     {
       assert(num_bits <= msp->bits);
       msp->tmp >>= num_bits;  // consume num_bits
@@ -711,15 +711,15 @@ namespace ojph {
     }
 
     //************************************************************************/
-    /** @brief Fetches 32 bits from the frwd_struct bitstream
+    /** @brief Fetches 32 bits from the frwd_struct64 bitstream
      *
      *  @tparam      X is the value fed in when the bitstream is exhausted.
      *               See frwd_read regarding the template
-     *  @param [in]  msp is a pointer to frwd_struct
+     *  @param [in]  msp is a pointer to frwd_struct64
      */
     template<int X>
     static inline 
-    ui32 frwd_fetch(frwd_struct *msp)
+    ui32 frwd_fetch(frwd_struct64 *msp)
     {
       if (msp->bits < 32)
       {
@@ -731,15 +731,15 @@ namespace ojph {
     }
 
     //************************************************************************/
-    /** @brief Fetches up to 64 bits from the frwd_struct bitstream
+    /** @brief Fetches up to 64 bits from the frwd_struct64 bitstream
      *
      *  @tparam      X is the value fed in when the bitstream is exhausted.
      *               See frwd_read regarding the template
-     *  @param [in]  msp is a pointer to frwd_struct
+     *  @param [in]  msp is a pointer to frwd_struct64
      */
     template<ui8 X>
     static inline 
-    ui64 frwd_fetch64(frwd_struct *msp)
+    ui64 frwd_fetch64(frwd_struct64 *msp)
     {
       while (msp->bits <= 56)
         frwd_read8<X>(msp);
@@ -1147,7 +1147,7 @@ namespace ojph {
         const int v_n_size = 512 + 4;
         ui64 v_n_scratch[v_n_size] = {0};  // 4+ kB
 
-        frwd_struct magsgn;
+        frwd_struct64 magsgn;
         frwd_init8<0xFF>(&magsgn, coded_data, lcup - scup);
 
         const ui16 *sp = scratch;
@@ -1415,7 +1415,7 @@ namespace ojph {
           // We add an extra 8 entries, just in case we need more
           ui16 prev_row_sig[256 + 8] = {0}; // 528 Bytes
 
-          frwd_struct sigprop;
+          frwd_struct64 sigprop;
           frwd_init<0>(&sigprop, coded_data + lengths1, (int)lengths2);
 
           for (ui32 y = 0; y < height; y += 4)
diff --git a/src/core/coding/ojph_block_decoder_avx2.cpp b/src/core/coding/ojph_block_decoder_avx2.cpp
index 156ba1a..ee47d03 100644
--- a/src/core/coding/ojph_block_decoder_avx2.cpp
+++ b/src/core/coding/ojph_block_decoder_avx2.cpp
@@ -582,7 +582,7 @@ namespace ojph {
     /** @brief State structure for reading and unstuffing of forward-growing
      *         bitstreams; these are: MagSgn and SPP bitstreams
      */
-    struct frwd_struct {
+    struct frwd_struct_avx2 {
       const ui8* data;  //!<pointer to bitstream
       ui8 tmp[48];      //!<temporary buffer of read data + 16 extra
       ui32 bits;        //!<number of bits stored in tmp
@@ -605,12 +605,12 @@ namespace ojph {
      *  Reading can go beyond the end of buffer by up to 16 bytes.
      *
      *  @tparam       X is the value fed in when the bitstream is exhausted
-     *  @param  [in]  msp is a pointer to frwd_struct structure
+     *  @param  [in]  msp is a pointer to frwd_struct_avx2 structure
      *
      */
     template<int X>
     static inline
-    void frwd_read(frwd_struct *msp)
+    void frwd_read(frwd_struct_avx2 *msp)
     {
       assert(msp->bits <= 128);
 
@@ -689,17 +689,17 @@ namespace ojph {
     }
 
     //************************************************************************/
-    /** @brief Initialize frwd_struct struct and reads some bytes
+    /** @brief Initialize frwd_struct_avx2 struct and reads some bytes
      *
      *  @tparam      X is the value fed in when the bitstream is exhausted.
      *               See frwd_read regarding the template
-     *  @param [in]  msp is a pointer to frwd_struct
+     *  @param [in]  msp is a pointer to frwd_struct_avx2
      *  @param [in]  data is a pointer to the start of data
      *  @param [in]  size is the number of byte in the bitstream
      */
     template<int X>
     static inline
-    void frwd_init(frwd_struct *msp, const ui8* data, int size)
+    void frwd_init(frwd_struct_avx2 *msp, const ui8* data, int size)
     {
       msp->data = data;
       _mm_storeu_si128((__m128i *)msp->tmp, _mm_setzero_si128());
@@ -714,13 +714,13 @@ namespace ojph {
     }
 
     //************************************************************************/
-    /** @brief Consume num_bits bits from the bitstream of frwd_struct
+    /** @brief Consume num_bits bits from the bitstream of frwd_struct_avx2
      *
-     *  @param [in]  msp is a pointer to frwd_struct
+     *  @param [in]  msp is a pointer to frwd_struct_avx2
      *  @param [in]  num_bits is the number of bit to consume
      */
     static inline
-    void frwd_advance(frwd_struct *msp, ui32 num_bits)
+    void frwd_advance(frwd_struct_avx2 *msp, ui32 num_bits)
     {
       assert(num_bits > 0 && num_bits <= msp->bits && num_bits < 128);
       msp->bits -= num_bits;
@@ -752,15 +752,15 @@ namespace ojph {
     }
 
     //************************************************************************/
-    /** @brief Fetches 32 bits from the frwd_struct bitstream
+    /** @brief Fetches 32 bits from the frwd_struct_avx2 bitstream
      *
      *  @tparam      X is the value fed in when the bitstream is exhausted.
      *               See frwd_read regarding the template
-     *  @param [in]  msp is a pointer to frwd_struct
+     *  @param [in]  msp is a pointer to frwd_struct_avx2
      */
     template<int X>
     static inline
-    __m128i frwd_fetch(frwd_struct *msp)
+    __m128i frwd_fetch(frwd_struct_avx2 *msp)
     {
       if (msp->bits <= 128)
       {
@@ -782,7 +782,7 @@ namespace ojph {
      *  @param vn       used for handling E values (stores v_n values)
      *  @return __m256i decoded two quads
      */
-    static inline __m256i decode_two_quad32_avx2(__m256i inf_u_q, __m256i U_q, frwd_struct* magsgn, ui32 p, __m128i& vn) {
+    static inline __m256i decode_two_quad32_avx2(__m256i inf_u_q, __m256i U_q, frwd_struct_avx2* magsgn, ui32 p, __m128i& vn) {
         __m256i row = _mm256_setzero_si256();
 
         // we keeps e_k, e_1, and rho in w2
@@ -896,7 +896,7 @@ namespace ojph {
      *  @return __m128i decoded quad
      */
 
-    static inline __m256i decode_four_quad16(const __m128i inf_u_q, __m128i U_q, frwd_struct* magsgn, ui32 p, __m128i& vn) {
+    static inline __m256i decode_four_quad16(const __m128i inf_u_q, __m128i U_q, frwd_struct_avx2* magsgn, ui32 p, __m128i& vn) {
 
         __m256i w0;     // workers
         __m256i insig;  // lanes hold FF's if samples are insignificant
@@ -1435,7 +1435,7 @@ namespace ojph {
         const int v_n_size = 512 + 16;
         ui32 v_n_scratch[2 * v_n_size] = {0}; // 4+ kB
 
-        frwd_struct magsgn;
+        frwd_struct_avx2 magsgn;
         frwd_init<0xFF>(&magsgn, coded_data, lcup - scup);
 
         const __m256i avx_mmsbp2 = _mm256_set1_epi32((int)mmsbp2);
@@ -1551,7 +1551,7 @@ namespace ojph {
         ui16 v_n_scratch[v_n_size] = {0}; // 1+ kB
         ui32 v_n_scratch_32[v_n_size] = {0}; // 2+ kB
 
-        frwd_struct magsgn;
+        frwd_struct_avx2 magsgn;
         frwd_init<0xFF>(&magsgn, coded_data, lcup - scup);
 
         {
@@ -1728,7 +1728,7 @@ namespace ojph {
           // We add an extra 8 entries, just in case we need more
           ui16 prev_row_sig[256 + 8] = {0}; // 528 Bytes
 
-          frwd_struct sigprop;
+          frwd_struct_avx2 sigprop;
           frwd_init<0>(&sigprop, coded_data + lengths1, (int)lengths2);
 
           for (ui32 y = 0; y < height; y += 4)
diff --git a/src/core/coding/ojph_block_decoder_ssse3.cpp b/src/core/coding/ojph_block_decoder_ssse3.cpp
index 9fa5800..93efc12 100644
--- a/src/core/coding/ojph_block_decoder_ssse3.cpp
+++ b/src/core/coding/ojph_block_decoder_ssse3.cpp
@@ -579,7 +579,7 @@ namespace ojph {
     /** @brief State structure for reading and unstuffing of forward-growing 
      *         bitstreams; these are: MagSgn and SPP bitstreams
      */
-    struct frwd_struct {
+    struct frwd_struct_ssse3 {
       const ui8* data;  //!<pointer to bitstream
       ui8 tmp[48];      //!<temporary buffer of read data + 16 extra
       ui32 bits;        //!<number of bits stored in tmp
@@ -602,12 +602,12 @@ namespace ojph {
      *  Reading can go beyond the end of buffer by up to 16 bytes.
      *
      *  @tparam       X is the value fed in when the bitstream is exhausted
-     *  @param  [in]  msp is a pointer to frwd_struct structure
+     *  @param  [in]  msp is a pointer to frwd_struct_ssse3 structure
      *
      */
     template<int X>
     static inline 
-    void frwd_read(frwd_struct *msp)
+    void frwd_read(frwd_struct_ssse3 *msp)
     {
       assert(msp->bits <= 128);
 
@@ -686,17 +686,17 @@ namespace ojph {
     }
 
     //************************************************************************/
-    /** @brief Initialize frwd_struct struct and reads some bytes
+    /** @brief Initialize frwd_struct_ssse3 struct and reads some bytes
      *  
      *  @tparam      X is the value fed in when the bitstream is exhausted.
      *               See frwd_read regarding the template
-     *  @param [in]  msp is a pointer to frwd_struct
+     *  @param [in]  msp is a pointer to frwd_struct_ssse3
      *  @param [in]  data is a pointer to the start of data
      *  @param [in]  size is the number of byte in the bitstream
      */
     template<int X>
     static inline 
-    void frwd_init(frwd_struct *msp, const ui8* data, int size)
+    void frwd_init(frwd_struct_ssse3 *msp, const ui8* data, int size)
     {
       msp->data = data;
       _mm_storeu_si128((__m128i *)msp->tmp, _mm_setzero_si128());
@@ -711,13 +711,13 @@ namespace ojph {
     }
 
     //************************************************************************/
-    /** @brief Consume num_bits bits from the bitstream of frwd_struct
+    /** @brief Consume num_bits bits from the bitstream of frwd_struct_ssse3
      *
-     *  @param [in]  msp is a pointer to frwd_struct
+     *  @param [in]  msp is a pointer to frwd_struct_ssse3
      *  @param [in]  num_bits is the number of bit to consume
      */
     static inline 
-    void frwd_advance(frwd_struct *msp, ui32 num_bits)
+    void frwd_advance(frwd_struct_ssse3 *msp, ui32 num_bits)
     {
       assert(num_bits > 0 && num_bits <= msp->bits && num_bits < 128);
       msp->bits -= num_bits;
@@ -749,15 +749,15 @@ namespace ojph {
     }
 
     //************************************************************************/
-    /** @brief Fetches 32 bits from the frwd_struct bitstream
+    /** @brief Fetches 32 bits from the frwd_struct_ssse3 bitstream
      *
      *  @tparam      X is the value fed in when the bitstream is exhausted.
      *               See frwd_read regarding the template
-     *  @param [in]  msp is a pointer to frwd_struct
+     *  @param [in]  msp is a pointer to frwd_struct_ssse3
      */
     template<int X>
     static inline
-    __m128i frwd_fetch(frwd_struct *msp)
+    __m128i frwd_fetch(frwd_struct_ssse3 *msp)
     {
       if (msp->bits <= 128)
       {
@@ -784,7 +784,7 @@ namespace ojph {
     template <int N>
     static inline 
     __m128i decode_one_quad32(const __m128i inf_u_q, __m128i U_q,
-                              frwd_struct* magsgn, ui32 p, __m128i& vn)
+                              frwd_struct_ssse3* magsgn, ui32 p, __m128i& vn)
     {
       __m128i w0;    // workers
       __m128i insig; // lanes hold FF's if samples are insignificant
@@ -894,7 +894,7 @@ namespace ojph {
      */
     static inline 
     __m128i decode_two_quad16(const __m128i inf_u_q, __m128i U_q, 
-                              frwd_struct* magsgn, ui32 p, __m128i& vn)
+                              frwd_struct_ssse3* magsgn, ui32 p, __m128i& vn)
     {
       __m128i w0;     // workers
       __m128i insig;  // lanes hold FF's if samples are insignificant
@@ -1389,7 +1389,7 @@ namespace ojph {
         const int v_n_size = 512 + 8;
         ui32 v_n_scratch[2 * v_n_size] = {0}; // 4+ kB
 
-        frwd_struct magsgn;
+        frwd_struct_ssse3 magsgn;
         frwd_init<0xFF>(&magsgn, coded_data, lcup - scup);
 
         {
@@ -1540,7 +1540,7 @@ namespace ojph {
         const int v_n_size = 512 + 8;
         ui16 v_n_scratch[2 * v_n_size] = {0}; // 2+ kB
 
-        frwd_struct magsgn;
+        frwd_struct_ssse3 magsgn;
         frwd_init<0xFF>(&magsgn, coded_data, lcup - scup);
 
         {
@@ -1753,7 +1753,7 @@ namespace ojph {
           // We add an extra 8 entries, just in case we need more
           ui16 prev_row_sig[256 + 8] = {0}; // 528 Bytes
 
-          frwd_struct sigprop;
+          frwd_struct_ssse3 sigprop;
           frwd_init<0>(&sigprop, coded_data + lengths1, (int)lengths2);
 
           for (ui32 y = 0; y < height; y += 4)
diff --git a/src/core/coding/ojph_block_encoder.cpp b/src/core/coding/ojph_block_encoder.cpp
index ffc9e8d..f9c8d89 100644
--- a/src/core/coding/ojph_block_encoder.cpp
+++ b/src/core/coding/ojph_block_encoder.cpp
@@ -254,8 +254,18 @@ namespace ojph {
     }
 
     /////////////////////////////////////////////////////////////////////////
-    static bool vlc_tables_initialized = vlc_init_tables();
-    static bool uvlc_tables_initialized = uvlc_init_tables();
+    static bool tables_initialized = false;
+
+    /////////////////////////////////////////////////////////////////////////
+    bool initialize_block_encoder_tables() {
+      if (!tables_initialized) {
+        memset(vlc_tbl0, 0, 2048 * sizeof(ui16));
+        memset(vlc_tbl1, 0, 2048 * sizeof(ui16));
+        tables_initialized = vlc_init_tables();
+        tables_initialized = tables_initialized && uvlc_init_tables();
+      }
+      return tables_initialized;
+    }
 
     /////////////////////////////////////////////////////////////////////////
     //
diff --git a/src/core/coding/ojph_block_encoder.h b/src/core/coding/ojph_block_encoder.h
index 72b3c0d..c0af892 100644
--- a/src/core/coding/ojph_block_encoder.h
+++ b/src/core/coding/ojph_block_encoder.h
@@ -79,6 +79,7 @@ namespace ojph {
                                    ojph::mem_elastic_allocator *elastic,
                                    ojph::coded_lists *& coded);
 
+    bool initialize_block_encoder_tables();
     bool initialize_block_encoder_tables_avx2();
     bool initialize_block_encoder_tables_avx512();
   }
diff --git a/src/core/coding/ojph_block_encoder_avx2.cpp b/src/core/coding/ojph_block_encoder_avx2.cpp
index 7624272..d9a76c2 100644
--- a/src/core/coding/ojph_block_encoder_avx2.cpp
+++ b/src/core/coding/ojph_block_encoder_avx2.cpp
@@ -305,7 +305,7 @@ namespace ojph {
     /////////////////////////////////////////////////////////////////////////
     //
     /////////////////////////////////////////////////////////////////////////
-    struct vlc_struct {
+    struct vlc_struct_avx2 {
       //storage
       ui8* buf;      //pointer to data buffer
       ui32 pos;      //position of next writing within buf
@@ -318,7 +318,7 @@ namespace ojph {
 
     //////////////////////////////////////////////////////////////////////////
     static inline void
-    vlc_init(vlc_struct* vlcp, ui32 buffer_size, ui8* data)
+    vlc_init(vlc_struct_avx2* vlcp, ui32 buffer_size, ui8* data)
     {
       vlcp->buf = data + buffer_size - 1; //points to last byte
       vlcp->pos = 1;                      //locations will be all -pos
@@ -332,7 +332,7 @@ namespace ojph {
 
     //////////////////////////////////////////////////////////////////////////
     static inline void
-    vlc_encode(vlc_struct* vlcp, ui32 cwd, int cwd_len)
+    vlc_encode(vlc_struct_avx2* vlcp, ui32 cwd, int cwd_len)
     {
       vlcp->tmp |= (ui64)cwd << vlcp->used_bits;
       vlcp->used_bits += cwd_len;
@@ -372,7 +372,7 @@ namespace ojph {
     //
     //////////////////////////////////////////////////////////////////////////
     static inline void
-    terminate_mel_vlc(mel_struct* melp, vlc_struct* vlcp)
+    terminate_mel_vlc(mel_struct* melp, vlc_struct_avx2* vlcp)
     {
       if (melp->run > 0)
         mel_emit_bit(melp, 1);
@@ -890,7 +890,7 @@ static void proc_mel_encode2(mel_struct *melp, __m256i &cq_vec,
 using fn_proc_mel_encode = void (*)(mel_struct *, __m256i &, __m256i &,
                                     __m256i, ui32, const __m256i);
 
-static void proc_vlc_encode1(vlc_struct *vlcp, ui32 *tuple,
+static void proc_vlc_encode1(vlc_struct_avx2 *vlcp, ui32 *tuple,
                              ui32 *u_q, ui32 ignore)
 {
     ui32 i_max = 8 - (ignore / 2);
@@ -958,7 +958,7 @@ static void proc_vlc_encode1(vlc_struct *vlcp, ui32 *tuple,
     }
 }
 
-static void proc_vlc_encode2(vlc_struct *vlcp, ui32 *tuple,
+static void proc_vlc_encode2(vlc_struct_avx2 *vlcp, ui32 *tuple,
                              ui32 *u_q, ui32 ignore)
 {
     ui32 i_max = 8 - (ignore / 2);
@@ -994,7 +994,7 @@ static void proc_vlc_encode2(vlc_struct *vlcp, ui32 *tuple,
     }
 }
 
-using fn_proc_vlc_encode = void (*)(vlc_struct *, ui32 *, ui32 *, ui32);
+using fn_proc_vlc_encode = void (*)(vlc_struct_avx2 *, ui32 *, ui32 *, ui32);
 
 void ojph_encode_codeblock_avx2(ui32* buf, ui32 missing_msbs,
                                 ui32 num_passes, ui32 _width, ui32 height,
@@ -1018,7 +1018,7 @@ void ojph_encode_codeblock_avx2(ui32* buf, ui32 missing_msbs,
 
     mel_struct mel;
     mel_init(&mel, mel_size, mel_buf);
-    vlc_struct vlc;
+    vlc_struct_avx2 vlc;
     vlc_init(&vlc, vlc_size, vlc_buf);
     ms_struct ms;
     ms_init(&ms, ms_size, ms_buf);
diff --git a/src/core/coding/ojph_block_encoder_avx512.cpp b/src/core/coding/ojph_block_encoder_avx512.cpp
index b35373a..5bcd433 100644
--- a/src/core/coding/ojph_block_encoder_avx512.cpp
+++ b/src/core/coding/ojph_block_encoder_avx512.cpp
@@ -305,7 +305,7 @@ namespace ojph {
     /////////////////////////////////////////////////////////////////////////
     //
     /////////////////////////////////////////////////////////////////////////
-    struct vlc_struct {
+    struct vlc_struct_avx512 {
       //storage
       ui8* buf;      //pointer to data buffer
       ui32 pos;      //position of next writing within buf
@@ -318,7 +318,7 @@ namespace ojph {
 
     //////////////////////////////////////////////////////////////////////////
     static inline void
-    vlc_init(vlc_struct* vlcp, ui32 buffer_size, ui8* data)
+    vlc_init(vlc_struct_avx512* vlcp, ui32 buffer_size, ui8* data)
     {
       vlcp->buf = data + buffer_size - 1; //points to last byte
       vlcp->pos = 1;                      //locations will be all -pos
@@ -332,7 +332,7 @@ namespace ojph {
 
     //////////////////////////////////////////////////////////////////////////
     static inline void
-    vlc_encode(vlc_struct* vlcp, ui32 cwd, int cwd_len)
+    vlc_encode(vlc_struct_avx512* vlcp, ui32 cwd, int cwd_len)
     {
       vlcp->tmp |= (ui64)cwd << vlcp->used_bits;
       vlcp->used_bits += cwd_len;
@@ -372,7 +372,7 @@ namespace ojph {
     //
     //////////////////////////////////////////////////////////////////////////
     static inline void
-    terminate_mel_vlc(mel_struct* melp, vlc_struct* vlcp)
+    terminate_mel_vlc(mel_struct* melp, vlc_struct_avx512* vlcp)
     {
       if (melp->run > 0)
         mel_emit_bit(melp, 1);
@@ -898,7 +898,7 @@ static void proc_mel_encode2(mel_struct *melp, __m512i &cq_vec,
 using fn_proc_mel_encode = void (*)(mel_struct *, __m512i &, __m512i &, 
                                     __m512i, ui32, const __m512i);
 
-static void proc_vlc_encode1(vlc_struct *vlcp, ui32 *tuple,
+static void proc_vlc_encode1(vlc_struct_avx512 *vlcp, ui32 *tuple,
                              ui32 *u_q, ui32 ignore)
 {
     ui32 i_max = 16 - (ignore / 2);
@@ -966,7 +966,7 @@ static void proc_vlc_encode1(vlc_struct *vlcp, ui32 *tuple,
     }
 }
 
-static void proc_vlc_encode2(vlc_struct *vlcp, ui32 *tuple,
+static void proc_vlc_encode2(vlc_struct_avx512 *vlcp, ui32 *tuple,
                              ui32 *u_q, ui32 ignore)
 {
     ui32 i_max = 16 - (ignore / 2);
@@ -1002,7 +1002,7 @@ static void proc_vlc_encode2(vlc_struct *vlcp, ui32 *tuple,
     }
 }
 
-using fn_proc_vlc_encode = void (*)(vlc_struct *, ui32 *, ui32 *, ui32);
+using fn_proc_vlc_encode = void (*)(vlc_struct_avx512 *, ui32 *, ui32 *, ui32);
 
 void ojph_encode_codeblock_avx512(ui32* buf, ui32 missing_msbs, 
                                   ui32 num_passes, ui32 _width, ui32 height, 
@@ -1026,7 +1026,7 @@ void ojph_encode_codeblock_avx512(ui32* buf, ui32 missing_msbs,
 
     mel_struct mel;
     mel_init(&mel, mel_size, mel_buf);
-    vlc_struct vlc;
+    vlc_struct_avx512 vlc;
     vlc_init(&vlc, vlc_size, vlc_buf);
     ms_struct ms;
     ms_init(&ms, ms_size, ms_buf);
diff --git a/src/core/common/ojph_version.h b/src/core/common/ojph_version.h
index 00faf75..44b59d4 100644
--- a/src/core/common/ojph_version.h
+++ b/src/core/common/ojph_version.h
@@ -35,4 +35,4 @@
 
 #define OPENJPH_VERSION_MAJOR 0
 #define OPENJPH_VERSION_MINOR 18
-#define OPENJPH_VERSION_PATCH 0
+#define OPENJPH_VERSION_PATCH 1
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 8cc1d72..547f1c5 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -17,9 +17,8 @@ FetchContent_Declare(
   jp2k_test_codestreams
   URL               https://github.com/aous72/jp2k_test_codestreams/archive/refs/heads/main.zip
   SOURCE_DIR        jp2k_test_codestreams/
-  CONFIGURE_COMMAND ""
 )
-FetchContent_Populate(jp2k_test_codestreams)
+FetchContent_MakeAvailable(jp2k_test_codestreams)
 
 # create the mse_pae executable
 include(mse_pae.cmake)