diff --git a/include/etl/private/bitset_new.h b/include/etl/private/bitset_new.h
index ef1152cd..841836a6 100644
--- a/include/etl/private/bitset_new.h
+++ b/include/etl/private/bitset_new.h
@@ -554,18 +554,18 @@ namespace etl
     //*************************************************************************
     /// Flip all of the bits.
     //*************************************************************************
-    static ETL_CONSTEXPR14 void flip_all(pointer pbuffer, size_t /*number_of_elements*/) ETL_NOEXCEPT
+    static ETL_CONSTEXPR14 void flip_all(pointer pbuffer, size_t /*number_of_elements*/, element_type top_mask) ETL_NOEXCEPT
     {
-      *pbuffer = ~*pbuffer;
+      *pbuffer = (~*pbuffer) & top_mask;
     }
 
     //*************************************************************************
     /// Flip some of the bits.
     //*************************************************************************
-    static ETL_CONSTEXPR14 void flip_bits(pointer pbuffer, element_type mask = etl::integral_limits<element_type>::max) ETL_NOEXCEPT
-    {
-      *pbuffer ^= mask;
-    }
+    // static ETL_CONSTEXPR14 void flip_bits(pointer pbuffer, element_type mask = etl::integral_limits<element_type>::max) ETL_NOEXCEPT
+    //{
+    //  *pbuffer ^= mask;
+    //}
 
     //*************************************************************************
     /// Flip the bit at the position.
@@ -1253,9 +1253,9 @@ namespace etl
     //*************************************************************************
     /// Flip all of the bits.
     //*************************************************************************
-    static ETL_CONSTEXPR14 void flip_all(pointer pbuffer, size_t number_of_elements) ETL_NOEXCEPT
+    static ETL_CONSTEXPR14 void flip_all(pointer pbuffer, size_t number_of_elements, element_type top_mask) ETL_NOEXCEPT
     {
-      operator_not(pbuffer, number_of_elements);
+      operator_not(pbuffer, number_of_elements, top_mask);
     }
 
     //*************************************************************************
@@ -1398,13 +1398,16 @@ namespace etl
     //*************************************************************************
     /// operator not
     //*************************************************************************
-    static ETL_CONSTEXPR14 void operator_not(pointer pbuffer, size_t number_of_elements) ETL_NOEXCEPT
+    static ETL_CONSTEXPR14 void operator_not(pointer pbuffer, size_t number_of_elements, element_type top_mask) ETL_NOEXCEPT
     {
       while (number_of_elements-- != 0)
       {
         *pbuffer = ~*pbuffer;
         ++pbuffer;
       }
+
+      --pbuffer;            // Step back to the last element.
+      *pbuffer &= top_mask; // Clear unused bits.
     }
 
     //*************************************************************************
@@ -2248,7 +2251,7 @@ namespace etl
     //*************************************************************************
     ETL_CONSTEXPR14 bitset<Active_Bits, TElement>& flip() ETL_NOEXCEPT
     {
-      implementation::flip_all(buffer, Number_Of_Elements);
+      implementation::flip_all(buffer, Number_Of_Elements, Top_Mask);
 
       return *this;
     }
@@ -2389,7 +2392,7 @@ namespace etl
     {
       etl::bitset<Active_Bits, TElement> temp(*this);
 
-      implementation::flip_all(temp.buffer, Number_Of_Elements);
+      implementation::flip_all(temp.buffer, Number_Of_Elements, Top_Mask);
 
       return temp;
     }
@@ -3245,7 +3248,7 @@ namespace etl
     //*************************************************************************
     ETL_CONSTEXPR14 bitset_ext<Active_Bits, TElement>& flip() ETL_NOEXCEPT
     {
-      implementation::flip_all(pbuffer, Number_Of_Elements);
+      implementation::flip_all(pbuffer, Number_Of_Elements, Top_Mask);
 
       return *this;
     }
diff --git a/test/test_bitset_legacy.cpp b/test/test_bitset_legacy.cpp
index 643dfc27..90056064 100644
--- a/test/test_bitset_legacy.cpp
+++ b/test/test_bitset_legacy.cpp
@@ -1505,13 +1505,13 @@ namespace
     {
       etl::bitset<5U> bits;
       std::bitset<5U> stdbits;
-      etl::bitset<5U> negbits    = ~bits;
-      std::bitset<5U> stdnegbits = ~stdbits;
+      etl::bitset<5U> negated_bits = ~bits;
+      std::bitset<5U> stdnegbits   = ~stdbits;
 
       CHECK_EQUAL(stdbits.count(), bits.count());
       CHECK_EQUAL(stdbits.all(), bits.all());
-      CHECK_EQUAL(stdnegbits.count(), negbits.count());
-      CHECK_EQUAL(stdnegbits.all(), negbits.all());
+      CHECK_EQUAL(stdnegbits.count(), negated_bits.count());
+      CHECK_EQUAL(stdnegbits.all(), negated_bits.all());
     }
 
     //*************************************************************************
diff --git a/test/test_bitset_new_default_element_type.cpp b/test/test_bitset_new_default_element_type.cpp
index 9ecd1bf6..0321519b 100644
--- a/test/test_bitset_new_default_element_type.cpp
+++ b/test/test_bitset_new_default_element_type.cpp
@@ -310,6 +310,8 @@ namespace
       {
         CHECK_EQUAL(compare.test(i), data.test(i));
       }
+
+      CHECK_EQUAL(compare.to_ullong(), data.to_ullong());
     }
 
     //*************************************************************************
@@ -325,6 +327,8 @@ namespace
       {
         CHECK_EQUAL(compare.test(i), data.test(i));
       }
+
+      CHECK_EQUAL(compare.to_ullong(), data.to_ullong());
     }
 
     //*************************************************************************
@@ -340,6 +344,8 @@ namespace
       {
         CHECK_EQUAL(compare.test(i), data.test(i));
       }
+
+      CHECK_EQUAL(compare.to_ullong(), data.to_ullong());
     }
 
     //*************************************************************************
@@ -355,54 +361,29 @@ namespace
       {
         CHECK_EQUAL(compare.test(i), data.test(i));
       }
+
+      CHECK_EQUAL(compare.to_ullong(), data.to_ullong());
     }
 
     //*************************************************************************
-    TEST(test_construct_from_nullptr_char_string)
+    TEST(test_construct_from_64_bit_char_string_where_the_bitset_size_is_60)
     {
-      const char* s = nullptr;
+      std::bitset<60> compare("110001001000110100010101100111001100010010001101000101011001");
+      etl::bitset<60> data("110001001000110100010101100111001100010010001101000101011001");
 
-      etl::bitset<60> data(s);
+      CHECK_EQUAL(compare.size(), data.size());
+      CHECK_EQUAL(compare.count(), data.count());
 
-      CHECK_EQUAL(60, data.size());
-      CHECK_EQUAL(0, data.count());
+      for (size_t i = 0UL; i < data.size(); ++i)
+      {
+        CHECK_EQUAL(compare.test(i), data.test(i));
+      }
+
+      CHECK_EQUAL(compare.to_ullong(), data.to_ullong());
     }
 
     //*************************************************************************
-    TEST(test_construct_from_nullptr_wchar_t_string)
-    {
-      const wchar_t* s = nullptr;
-
-      etl::bitset<60> data(s);
-
-      CHECK_EQUAL(60, data.size());
-      CHECK_EQUAL(0, data.count());
-    }
-
-    //*************************************************************************
-    TEST(test_construct_from_nullptr_char16_t_string)
-    {
-      const char16_t* s = nullptr;
-
-      etl::bitset<60> data(s);
-
-      CHECK_EQUAL(60, data.size());
-      CHECK_EQUAL(0, data.count());
-    }
-
-    //*************************************************************************
-    TEST(test_construct_from_nullptr_char32_t_string)
-    {
-      const char32_t* s = nullptr;
-
-      etl::bitset<60> data(s);
-
-      CHECK_EQUAL(60, data.size());
-      CHECK_EQUAL(0, data.count());
-    }
-
-    //*************************************************************************
-    TEST(test_construct_from_excess_string)
+    TEST(test_construct_from_69_bit_char_string_where_the_bitset_size_is_64)
     {
       std::bitset<64> compare("110001001000110100010101100111001100010010001101000101011001111100001");
       etl::bitset<64> data("110001001000110100010101100111001100010010001101000101011001111100001");
@@ -419,6 +400,56 @@ namespace
       {
         CHECK_EQUAL(compare.test(i), data.test(i));
       }
+
+      CHECK_EQUAL(compare.to_ullong(), data.to_ullong());
+    }
+
+    //*************************************************************************
+    TEST(test_construct_from_nullptr_char_string)
+    {
+      const char* s = nullptr;
+
+      etl::bitset<60> data(s);
+
+      CHECK_EQUAL(60, data.size());
+      CHECK_EQUAL(0, data.count());
+      CHECK_EQUAL(0, data.to_ullong());
+    }
+
+    //*************************************************************************
+    TEST(test_construct_from_nullptr_wchar_t_string)
+    {
+      const wchar_t* s = nullptr;
+
+      etl::bitset<60> data(s);
+
+      CHECK_EQUAL(60, data.size());
+      CHECK_EQUAL(0, data.count());
+      CHECK_EQUAL(0, data.to_ullong());
+    }
+
+    //*************************************************************************
+    TEST(test_construct_from_nullptr_char16_t_string)
+    {
+      const char16_t* s = nullptr;
+
+      etl::bitset<60> data(s);
+
+      CHECK_EQUAL(60, data.size());
+      CHECK_EQUAL(0, data.count());
+      CHECK_EQUAL(0, data.to_ullong());
+    }
+
+    //*************************************************************************
+    TEST(test_construct_from_nullptr_char32_t_string)
+    {
+      const char32_t* s = nullptr;
+
+      etl::bitset<60> data(s);
+
+      CHECK_EQUAL(60, data.size());
+      CHECK_EQUAL(0, data.count());
+      CHECK_EQUAL(0, data.to_ullong());
     }
 
     //*************************************************************************
@@ -2710,5 +2741,42 @@ namespace
 
       CHECK_EQUAL(32, ETL_OR_STD17::size(b));
     }
+
+    //*************************************************************************
+    TEST(test_issue_497)
+    {
+      etl::bitset<11, uint8_t> bits;
+
+      // Check the initial state of the bitset.
+      size_t count_set  = bits.count();
+      size_t count_size = bits.size();
+      bool   all_set    = bits.all();
+
+      CHECK_EQUAL(0, count_set);
+      CHECK_EQUAL(11, count_size);
+      CHECK_EQUAL(false, all_set);
+
+      // Copy flipped bits to a new bitset.
+      etl::bitset<11, uint8_t> negated_bits = ~bits;
+
+      count_set  = negated_bits.count();
+      count_size = negated_bits.size();
+      all_set    = negated_bits.all();
+
+      CHECK_EQUAL(11, count_set);
+      CHECK_EQUAL(11, count_size);
+      CHECK_EQUAL(true, all_set);
+
+      // Flip the bits in the original bitset.
+      bits.flip();
+
+      count_set  = bits.count();
+      count_size = bits.size();
+      all_set    = bits.all();
+
+      CHECK_EQUAL(11, count_set);
+      CHECK_EQUAL(11, count_size);
+      CHECK_EQUAL(true, all_set);
+    }
   }
 } // namespace
diff --git a/test/test_bitset_new_explicit_single_element_type.cpp b/test/test_bitset_new_explicit_single_element_type.cpp
index 3a44690b..3d32174d 100644
--- a/test/test_bitset_new_explicit_single_element_type.cpp
+++ b/test/test_bitset_new_explicit_single_element_type.cpp
@@ -307,6 +307,8 @@ namespace
       {
         CHECK_EQUAL(compare.test(i), data.test(i));
       }
+
+      CHECK_EQUAL(compare.to_ullong(), data.to_ullong());
     }
 
     //*************************************************************************
@@ -322,6 +324,8 @@ namespace
       {
         CHECK_EQUAL(compare.test(i), data.test(i));
       }
+
+      CHECK_EQUAL(compare.to_ullong(), data.to_ullong());
     }
 
     //*************************************************************************
@@ -337,6 +341,8 @@ namespace
       {
         CHECK_EQUAL(compare.test(i), data.test(i));
       }
+
+      CHECK_EQUAL(compare.to_ullong(), data.to_ullong());
     }
 
     //*************************************************************************
@@ -352,6 +358,47 @@ namespace
       {
         CHECK_EQUAL(compare.test(i), data.test(i));
       }
+
+      CHECK_EQUAL(compare.to_ullong(), data.to_ullong());
+    }
+
+    //*************************************************************************
+    TEST(test_construct_from_64_bit_char_string_where_the_bitset_size_is_60)
+    {
+      std::bitset<60> compare("110001001000110100010101100111001100010010001101000101011001");
+      etl::bitset<60> data("110001001000110100010101100111001100010010001101000101011001");
+
+      CHECK_EQUAL(compare.size(), data.size());
+      CHECK_EQUAL(compare.count(), data.count());
+
+      for (size_t i = 0UL; i < data.size(); ++i)
+      {
+        CHECK_EQUAL(compare.test(i), data.test(i));
+      }
+
+      CHECK_EQUAL(compare.to_ullong(), data.to_ullong());
+    }
+
+    //*************************************************************************
+    TEST(test_construct_from_69_bit_char_string_where_the_bitset_size_is_64)
+    {
+      std::bitset<64>           compare("110001001000110100010101100111001100010010001101000101011001111100001");
+      etl::bitset<64, uint64_t> data("110001001000110100010101100111001100010010001101000101011001111100001");
+
+      CHECK_EQUAL(compare.size(), data.size());
+      CHECK_EQUAL(compare.count(), data.count());
+      CHECK_EQUAL(compare.none(), data.none());
+      CHECK_EQUAL(compare.any(), data.any());
+      CHECK_EQUAL(compare.all(), data.all());
+
+      CHECK_EQUAL_HEX(compare.to_ullong(), data.to_ullong());
+
+      for (size_t i = 0UL; i < data.size(); ++i)
+      {
+        CHECK_EQUAL(compare.test(i), data.test(i));
+      }
+
+      CHECK_EQUAL(compare.to_ullong(), data.to_ullong());
     }
 
     //*************************************************************************
@@ -412,26 +459,11 @@ namespace
       CHECK_EQUAL(0U, data_wchar.count());
       CHECK_EQUAL(0U, data_u16.count());
       CHECK_EQUAL(0U, data_u32.count());
-    }
 
-    //*************************************************************************
-    TEST(test_construct_from_excess_string)
-    {
-      std::bitset<64>           compare("110001001000110100010101100111001100010010001101000101011001111100001");
-      etl::bitset<64, uint64_t> data("110001001000110100010101100111001100010010001101000101011001111100001");
-
-      CHECK_EQUAL(compare.size(), data.size());
-      CHECK_EQUAL(compare.count(), data.count());
-      CHECK_EQUAL(compare.none(), data.none());
-      CHECK_EQUAL(compare.any(), data.any());
-      CHECK_EQUAL(compare.all(), data.all());
-
-      CHECK_EQUAL_HEX(compare.to_ullong(), data.to_ullong());
-
-      for (size_t i = 0UL; i < data.size(); ++i)
-      {
-        CHECK_EQUAL(compare.test(i), data.test(i));
-      }
+      CHECK_EQUAL(0U, data_char.to_ullong());
+      CHECK_EQUAL(0U, data_wchar.to_ullong());
+      CHECK_EQUAL(0U, data_u16.to_ullong());
+      CHECK_EQUAL(0U, data_u32.to_ullong());
     }
 
     //*************************************************************************
@@ -2840,5 +2872,42 @@ namespace
 
       CHECK_EQUAL(32, ETL_OR_STD17::size(b));
     }
+
+    //*************************************************************************
+    TEST(test_issue_497)
+    {
+      etl::bitset<5, uint8_t> bits;
+
+      // Check the initial state of the bitset.
+      size_t count_set  = bits.count();
+      size_t count_size = bits.size();
+      bool   all_set    = bits.all();
+
+      CHECK_EQUAL(0, count_set);
+      CHECK_EQUAL(5, count_size);
+      CHECK_EQUAL(false, all_set);
+
+      // Copy flipped bits to a new bitset.
+      etl::bitset<5, uint8_t> negated_bits = ~bits;
+
+      count_set  = negated_bits.count();
+      count_size = negated_bits.size();
+      all_set    = negated_bits.all();
+
+      CHECK_EQUAL(5, count_set);
+      CHECK_EQUAL(5, count_size);
+      CHECK_EQUAL(true, all_set);
+
+      // Flip the bits in the original bitset.
+      bits.flip();
+
+      count_set  = bits.count();
+      count_size = bits.size();
+      all_set    = bits.all();
+
+      CHECK_EQUAL(5, count_set);
+      CHECK_EQUAL(5, count_size);
+      CHECK_EQUAL(true, all_set);
+    }
   }
 } // namespace
diff --git a/test/test_bitset_new_ext_default_element_type.cpp b/test/test_bitset_new_ext_default_element_type.cpp
index d506b8f3..dfa5c5aa 100644
--- a/test/test_bitset_new_ext_default_element_type.cpp
+++ b/test/test_bitset_new_ext_default_element_type.cpp
@@ -251,6 +251,8 @@ namespace
       {
         CHECK_EQUAL(compare.test(i), data.test(i));
       }
+
+      CHECK_EQUAL(compare.to_ullong(), data.to_ullong());
     }
 
     //*************************************************************************
@@ -267,6 +269,8 @@ namespace
       {
         CHECK_EQUAL(compare.test(i), data.test(i));
       }
+
+      CHECK_EQUAL(compare.to_ullong(), data.to_ullong());
     }
 
     //*************************************************************************
@@ -283,6 +287,8 @@ namespace
       {
         CHECK_EQUAL(compare.test(i), data.test(i));
       }
+
+      CHECK_EQUAL(compare.to_ullong(), data.to_ullong());
     }
 
     //*************************************************************************
@@ -299,6 +305,49 @@ namespace
       {
         CHECK_EQUAL(compare.test(i), data.test(i));
       }
+
+      CHECK_EQUAL(compare.to_ullong(), data.to_ullong());
+    }
+
+    //*************************************************************************
+    TEST(test_construct_from_64_bit_char_string_where_the_bitset_size_is_60)
+    {
+      etl::bitset_ext<64>::buffer_type buffer;
+      std::bitset<60>                  compare("110001001000110100010101100111001100010010001101000101011001");
+      etl::bitset_ext<60>              data("110001001000110100010101100111001100010010001101000101011001", buffer);
+
+      CHECK_EQUAL(compare.size(), data.size());
+      CHECK_EQUAL(compare.count(), data.count());
+
+      for (size_t i = 0UL; i < data.size(); ++i)
+      {
+        CHECK_EQUAL(compare.test(i), data.test(i));
+      }
+
+      CHECK_EQUAL(compare.to_ullong(), data.to_ullong());
+    }
+
+    //*************************************************************************
+    TEST(test_construct_from_69_bit_char_string_where_the_bitset_size_is_64)
+    {
+      etl::bitset_ext<64>::buffer_type buffer;
+      std::bitset<64>                  compare("110001001000110100010101100111001100010010001101000101011001111100001");
+      etl::bitset_ext<64>              data("110001001000110100010101100111001100010010001101000101011001111100001", buffer);
+
+      CHECK_EQUAL(compare.size(), data.size());
+      CHECK_EQUAL(compare.count(), data.count());
+      CHECK_EQUAL(compare.none(), data.none());
+      CHECK_EQUAL(compare.any(), data.any());
+      CHECK_EQUAL(compare.all(), data.all());
+
+      CHECK_EQUAL_HEX(compare.to_ullong(), data.to_ullong());
+
+      for (size_t i = 0UL; i < data.size(); ++i)
+      {
+        CHECK_EQUAL(compare.test(i), data.test(i));
+      }
+
+      CHECK_EQUAL(compare.to_ullong(), data.to_ullong());
     }
 
     //*************************************************************************
@@ -349,27 +398,6 @@ namespace
       CHECK_EQUAL(0, data.count());
     }
 
-    //*************************************************************************
-    TEST(test_construct_from_excess_string)
-    {
-      etl::bitset_ext<64>::buffer_type buffer;
-      std::bitset<64>                  compare("110001001000110100010101100111001100010010001101000101011001111100001");
-      etl::bitset_ext<64>              data("110001001000110100010101100111001100010010001101000101011001111100001", buffer);
-
-      CHECK_EQUAL(compare.size(), data.size());
-      CHECK_EQUAL(compare.count(), data.count());
-      CHECK_EQUAL(compare.none(), data.none());
-      CHECK_EQUAL(compare.any(), data.any());
-      CHECK_EQUAL(compare.all(), data.all());
-
-      CHECK_EQUAL_HEX(compare.to_ullong(), data.to_ullong());
-
-      for (size_t i = 0UL; i < data.size(); ++i)
-      {
-        CHECK_EQUAL(compare.test(i), data.test(i));
-      }
-    }
-
     //*************************************************************************
     TEST(test_set)
     {
@@ -2460,5 +2488,42 @@ namespace
 
       CHECK_EQUAL(32, ETL_OR_STD17::size(b));
     }
+
+    //*************************************************************************
+    TEST(test_issue_497)
+    {
+      etl::bitset_ext<11>::buffer_type buffer1;
+      etl::bitset_ext<11>              bits(buffer1);
+
+      // Check the initial state of the bitset.
+      size_t count_set  = bits.count();
+      size_t count_size = bits.size();
+      bool   all_set    = bits.all();
+
+      CHECK_EQUAL(0, count_set);
+      CHECK_EQUAL(11, count_size);
+      CHECK_EQUAL(false, all_set);
+
+      // Copy flipped bits to a new bitset.
+      etl::bitset_ext<11>::buffer_type buffer2;
+      etl::bitset_ext<11>              negated_bits(bits.flip(), buffer2);
+
+      count_set  = negated_bits.count();
+      count_size = negated_bits.size();
+      all_set    = negated_bits.all();
+
+      CHECK_EQUAL(11, count_set);
+      CHECK_EQUAL(11, count_size);
+      CHECK_EQUAL(true, all_set);
+
+      // Test the flipped the bits in the original bitset.
+      count_set  = bits.count();
+      count_size = bits.size();
+      all_set    = bits.all();
+
+      CHECK_EQUAL(11, count_set);
+      CHECK_EQUAL(11, count_size);
+      CHECK_EQUAL(true, all_set);
+    }
   }
 } // namespace
diff --git a/test/test_bitset_new_ext_explicit_single_element_type.cpp b/test/test_bitset_new_ext_explicit_single_element_type.cpp
index e51ccb7e..889ff78c 100644
--- a/test/test_bitset_new_ext_explicit_single_element_type.cpp
+++ b/test/test_bitset_new_ext_explicit_single_element_type.cpp
@@ -279,6 +279,8 @@ namespace
       {
         CHECK_EQUAL(compare.test(i), data.test(i));
       }
+
+      CHECK_EQUAL(compare.to_ullong(), data.to_ullong());
     }
 
     //*************************************************************************
@@ -295,6 +297,8 @@ namespace
       {
         CHECK_EQUAL(compare.test(i), data.test(i));
       }
+
+      CHECK_EQUAL(compare.to_ullong(), data.to_ullong());
     }
 
     //*************************************************************************
@@ -311,6 +315,8 @@ namespace
       {
         CHECK_EQUAL(compare.test(i), data.test(i));
       }
+
+      CHECK_EQUAL(compare.to_ullong(), data.to_ullong());
     }
 
     //*************************************************************************
@@ -327,6 +333,49 @@ namespace
       {
         CHECK_EQUAL(compare.test(i), data.test(i));
       }
+
+      CHECK_EQUAL(compare.to_ullong(), data.to_ullong());
+    }
+
+    //*************************************************************************
+    TEST(test_construct_from_64_bit_char_string_where_the_bitset_size_is_60)
+    {
+      etl::bitset_ext<64, uint64_t>::buffer_type buffer;
+      std::bitset<60>                            compare("110001001000110100010101100111001100010010001101000101011001");
+      etl::bitset_ext<60, uint64_t>              data("110001001000110100010101100111001100010010001101000101011001", buffer);
+
+      CHECK_EQUAL(compare.size(), data.size());
+      CHECK_EQUAL(compare.count(), data.count());
+
+      for (size_t i = 0UL; i < data.size(); ++i)
+      {
+        CHECK_EQUAL(compare.test(i), data.test(i));
+      }
+
+      CHECK_EQUAL(compare.to_ullong(), data.to_ullong());
+    }
+
+    //*************************************************************************
+    TEST(test_construct_from_69_bit_char_string_where_the_bitset_size_is_64)
+    {
+      etl::bitset_ext<64, uint64_t>::buffer_type buffer;
+      std::bitset<64>                            compare("110001001000110100010101100111001100010010001101000101011001111100001");
+      etl::bitset_ext<64, uint64_t>              data("110001001000110100010101100111001100010010001101000101011001111100001", buffer);
+
+      CHECK_EQUAL(compare.size(), data.size());
+      CHECK_EQUAL(compare.count(), data.count());
+      CHECK_EQUAL(compare.none(), data.none());
+      CHECK_EQUAL(compare.any(), data.any());
+      CHECK_EQUAL(compare.all(), data.all());
+
+      CHECK_EQUAL_HEX(compare.to_ullong(), data.to_ullong());
+
+      for (size_t i = 0UL; i < data.size(); ++i)
+      {
+        CHECK_EQUAL(compare.test(i), data.test(i));
+      }
+
+      CHECK_EQUAL(compare.to_ullong(), data.to_ullong());
     }
 
     //*************************************************************************
@@ -377,27 +426,6 @@ namespace
       CHECK_EQUAL(0, data.count());
     }
 
-    //*************************************************************************
-    TEST(test_construct_from_excess_string)
-    {
-      etl::bitset_ext<64, uint64_t>::buffer_type buffer;
-      std::bitset<64>                            compare("110001001000110100010101100111001100010010001101000101011001111100001");
-      etl::bitset_ext<64, uint64_t>              data("110001001000110100010101100111001100010010001101000101011001111100001", buffer);
-
-      CHECK_EQUAL(compare.size(), data.size());
-      CHECK_EQUAL(compare.count(), data.count());
-      CHECK_EQUAL(compare.none(), data.none());
-      CHECK_EQUAL(compare.any(), data.any());
-      CHECK_EQUAL(compare.all(), data.all());
-
-      CHECK_EQUAL_HEX(compare.to_ullong(), data.to_ullong());
-
-      for (size_t i = 0UL; i < data.size(); ++i)
-      {
-        CHECK_EQUAL(compare.test(i), data.test(i));
-      }
-    }
-
     //*************************************************************************
     TEST(test_set)
     {
@@ -2629,4 +2657,41 @@ namespace
       CHECK_EQUAL(32, ETL_OR_STD17::size(b));
     }
   }
+
+  //*************************************************************************
+  TEST(test_issue_497)
+  {
+    etl::bitset_ext<11, uint8_t>::buffer_type buffer1;
+    etl::bitset_ext<11, uint8_t>              bits(buffer1);
+
+    // Check the initial state of the bitset.
+    size_t count_set  = bits.count();
+    size_t count_size = bits.size();
+    bool   all_set    = bits.all();
+
+    CHECK_EQUAL(0, count_set);
+    CHECK_EQUAL(11, count_size);
+    CHECK_EQUAL(false, all_set);
+
+    // Copy flipped bits to a new bitset.
+    etl::bitset_ext<11, uint8_t>::buffer_type buffer2;
+    etl::bitset_ext<11, uint8_t>              negated_bits(bits.flip(), buffer2);
+
+    count_set  = negated_bits.count();
+    count_size = negated_bits.size();
+    all_set    = negated_bits.all();
+
+    CHECK_EQUAL(11, count_set);
+    CHECK_EQUAL(11, count_size);
+    CHECK_EQUAL(true, all_set);
+
+    // Test the flipped the bits in the original bitset.
+    count_set  = bits.count();
+    count_size = bits.size();
+    all_set    = bits.all();
+
+    CHECK_EQUAL(11, count_set);
+    CHECK_EQUAL(11, count_size);
+    CHECK_EQUAL(true, all_set);
+  }
 } // namespace