diff --git a/libs/libopenfpgautil/src/openfpga_decode.cpp b/libs/libopenfpgautil/src/openfpga_decode.cpp
index 988bec456..30aa2d128 100644
--- a/libs/libopenfpgautil/src/openfpga_decode.cpp
+++ b/libs/libopenfpgautil/src/openfpga_decode.cpp
@@ -2,10 +2,10 @@
  * This file includes functions that are used to decode integer to binary
  *vectors or the reverse operation
  ***************************************************************************************/
-#include <cmath>
 
 /* Headers from vtrutil library */
 #include "openfpga_decode.h"
+
 #include "vtr_assert.h"
 
 /* begin namespace openfpga */
@@ -109,12 +109,28 @@ std::string combine_two_1hot_str(const std::string& code1,
  *   Output:
  *     index | 0 | 1 | 2
  *     ret   | 0 | 0 | 1
+ *
+ *  ToDo: Need to revisit and change all the feature that call to this function
+ *            Had studied the code, should be safe to make the change
+ *            Apparently we only want to store 0 or 1 (binary vector)
+ *            Yet we store it in a vector on size_t (8 Bytes)
+ *            We are using 8x memory that we supposed to
+ *            uint8_t is good enough
+ *            Not a bug, but is a serious unoptimized issue
  ********************************************************************/
 std::vector<size_t> itobin_vec(const size_t& in_int, const size_t& bin_len) {
+  /* bin_len must be in valid range*/
+  VTR_ASSERT(bin_len > 0 && bin_len <= 64);
   std::vector<size_t> ret(bin_len, 0);
 
   /* Make sure we do not have any overflow! */
-  VTR_ASSERT((in_int < pow(2., bin_len)));
+  /* If the length is 64 bits, in_int can be any number since this is the max
+     bit length, and BTW pow(2, 64) itself should be zero (from 64bits size_t
+     perspective). Once we fix the bintoi_charvec() bug, without this change, it
+     will cause assertion */
+  if (bin_len < 64) {
+    VTR_ASSERT(in_int < (size_t(1) << bin_len));
+  }
 
   size_t temp = in_int;
   for (size_t i = 0; i < bin_len; i++) {
@@ -140,10 +156,18 @@ std::vector<size_t> itobin_vec(const size_t& in_int, const size_t& bin_len) {
  * which has a smaller memory footprint than size_t
  ********************************************************************/
 std::vector<char> itobin_charvec(const size_t& in_int, const size_t& bin_len) {
+  /* bin_len must be in valid range*/
+  VTR_ASSERT(bin_len > 0 && bin_len <= 64);
   std::vector<char> ret(bin_len, '0');
 
   /* Make sure we do not have any overflow! */
-  VTR_ASSERT((in_int < pow(2., bin_len)));
+  /* If the length is 64 bits, in_int can be any number since this is the max
+     bit length, and BTW pow(2, 64) itself should be zero (from 64bits size_t
+     perspective). Once we fix the bintoi_charvec() bug, without this change, it
+     will cause assertion */
+  if (bin_len < 64) {
+    VTR_ASSERT(in_int < (size_t(1) << bin_len));
+  }
 
   size_t temp = in_int;
   for (size_t i = 0; i < bin_len; i++) {
@@ -170,11 +194,14 @@ std::vector<char> itobin_charvec(const size_t& in_int, const size_t& bin_len) {
  * which has a smaller memory footprint than size_t
  ********************************************************************/
 size_t bintoi_charvec(const std::vector<char>& bin) {
+  /* bin.size() must be in valid range*/
+  VTR_ASSERT(bin.size() > 0 && bin.size() <= 64);
+
   size_t ret = 0;
 
   for (size_t i = 0; i < bin.size(); ++i) {
     if ('1' == bin[i]) {
-      ret += pow(2., i);
+      ret |= ((size_t)(1) << i);
     }
   }