diff --git a/.github/workflows/codecov.yml b/.github/workflows/codecov.yml
index 5f1a02ec2..fbf7841a0 100644
--- a/.github/workflows/codecov.yml
+++ b/.github/workflows/codecov.yml
@@ -3,6 +3,7 @@
 # Copyright 2021 Alexander Grund
 # Copyright 2022 James E. King III
 # Copyright 2023 Matt Borland
+# Copyright 2026 Christopher Kormanyos
 #
 # Distributed under the Boost Software License, Version 1.0.
 # (See accompanying file LICENSE_1_0.txt or copy at http://boost.org/LICENSE_1_0.txt)
@@ -93,7 +94,7 @@ jobs:
           fi
           git config --global pack.threads 0
 
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
         with:
           # For coverage builds fetch the whole history, else only 1 commit using a 'fake ternary'
           fetch-depth: ${{ matrix.coverage && '0' || '1' }}
@@ -107,7 +108,7 @@ jobs:
           restore-keys: ${{matrix.os}}-${{matrix.container}}-${{matrix.compiler}}-
 
       - name: Fetch Boost.CI
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           repository: boostorg/boost-ci
           ref: master
diff --git a/.github/workflows/multiprecision.yml b/.github/workflows/multiprecision.yml
index 391708eb4..99220e544 100644
--- a/.github/workflows/multiprecision.yml
+++ b/.github/workflows/multiprecision.yml
@@ -1,7 +1,7 @@
 # Copyright 2020 Evan Miller
 # Copyright 2020 Matt Borland
 # Copyright 2021 John Maddock
-# Copyright 2021 Christopher Kormanyos
+# Copyright 2021, 2026 Christopher Kormanyos
 # Distributed under the Boost Software License, Version 1.0.
 # (See accompanying file LICENSE_1_0.txt or copy at http://boost.org/LICENSE_1_0.txt)
 
@@ -31,7 +31,7 @@ jobs:
         compiler: [ g++-14 ]
         suite: [ specfun_mpfr, specfun_gmp, specfun_cpp_dec_float, specfun_cpp_bin_float, specfun_float128, specfun_cpp_double_double ]
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
         with:
           fetch-depth: '0'
       - name: Set TOOLSET
@@ -93,7 +93,7 @@ jobs:
         standard: [ c++14, c++17 ]
         suite: [ github_ci_block_1, github_ci_block_2 ]
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
         with:
           fetch-depth: '0'
       - name: Set TOOLSET
@@ -155,7 +155,7 @@ jobs:
         standard: [ c++17, c++20 ]
         suite: [ specfun_mpfr, specfun_gmp, specfun_cpp_dec_float, specfun_float128, specfun_cpp_double_double ]
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
         with:
           fetch-depth: '0'
       - name: Set TOOLSET
@@ -217,7 +217,7 @@ jobs:
         standard: [ c++14, c++17, c++20, c++23 ]
         suite: [ standalone ]
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
         with:
           fetch-depth: '0'
       - name: Set TOOLSET
@@ -279,7 +279,7 @@ jobs:
         standard: [ c++20 ]
         suite: [ arithmetic_tests, functions_and_limits, conversions, cpp_int_tests, misc ]
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
         with:
           fetch-depth: '0'
       - name: Set TOOLSET
@@ -341,7 +341,7 @@ jobs:
         standard: [ c++20 ]
         suite: [ arithmetic_tests, functions_and_limits, misc ]
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
         with:
           fetch-depth: '0'
       - name: Set TOOLSET
@@ -405,7 +405,7 @@ jobs:
         standard: [ 14, 17 ]
         suite: [ github_ci_block_1, github_ci_block_2 ]
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
         with:
           fetch-depth: '0'
       - name: Checkout main boost
@@ -448,7 +448,7 @@ jobs:
         standard: [ 14, 17, 20 ]
         suite: [ github_ci_block_1, github_ci_block_2 ]
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
         with:
           fetch-depth: '0'
       - name: Checkout main boost
@@ -486,7 +486,7 @@ jobs:
         standard: [ 14, 17, 2a ]
         suite: [ github_ci_block_1, github_ci_block_2 ]
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
         with:
           fetch-depth: '0'
       - name: Checkout main boost
diff --git a/include/boost/multiprecision/cpp_int.hpp b/include/boost/multiprecision/cpp_int.hpp
index efcf50cad..f6bfdc433 100644
--- a/include/boost/multiprecision/cpp_int.hpp
+++ b/include/boost/multiprecision/cpp_int.hpp
@@ -1,6 +1,6 @@
 ////////////////////////////////////////////////////////////////
 //  Copyright 2012 - 2022 John Maddock.
-//  Copyright 2022 Christopher Kormanyos.
+//  Copyright 2022, 2026 Christopher Kormanyos.
 //  Distributed under the Boost Software License,
 //  Version 1.0. (See accompanying file LICENSE_1_0.txt
 //  or copy at https://www.boost.org/LICENSE_1_0.txt)
@@ -393,14 +393,14 @@ struct cpp_int_base<MinBits, MaxBits, signed_magnitude, Checked, Allocator, fals
          m_limbs = new_size;
       }
    }
-   BOOST_MP_FORCEINLINE void normalize() noexcept
+   BOOST_MP_FORCEINLINE constexpr void normalize() noexcept
    {
       limb_pointer p = limbs();
       while ((m_limbs - 1) && !p[m_limbs - 1])
          --m_limbs;
    }
    BOOST_MP_FORCEINLINE constexpr cpp_int_base() noexcept : m_data(), m_limbs(1), m_sign(false), m_internal(true), m_alias(false){}
-   BOOST_MP_FORCEINLINE                 cpp_int_base(const cpp_int_base& o) : base_type(o), m_limbs(o.m_alias ? o.m_limbs : 0), m_sign(o.m_sign), m_internal(o.m_alias ? false : true), m_alias(o.m_alias)
+   BOOST_MP_FORCEINLINE           cpp_int_base(const cpp_int_base& o) : base_type(o), m_limbs(o.m_alias ? o.m_limbs : 0), m_sign(o.m_sign), m_internal(o.m_alias ? false : true), m_alias(o.m_alias)
    {
       if (m_alias)
       {
diff --git a/include/boost/multiprecision/cpp_int/literals.hpp b/include/boost/multiprecision/cpp_int/literals.hpp
index 0531f0a30..a3002b319 100644
--- a/include/boost/multiprecision/cpp_int/literals.hpp
+++ b/include/boost/multiprecision/cpp_int/literals.hpp
@@ -1,5 +1,7 @@
 ///////////////////////////////////////////////////////////////
-//  Copyright 2013 John Maddock. Distributed under the Boost
+//  Copyright 2013 John Maddock.
+//  Copyright 2026 Christopher Kormanyos
+//  Distributed under the Boost
 //  Software License, Version 1.0. (See accompanying file
 //  LICENSE_1_0.txt or copy at https://www.boost.org/LICENSE_1_0.txt
 
@@ -255,21 +257,24 @@ constexpr typename boost::multiprecision::literals::detail::unsigned_cpp_int_lit
    constexpr boost::multiprecision::number<boost::multiprecision::backends::cpp_int_backend<Bits, Bits, boost::multiprecision::signed_magnitude, boost::multiprecision::unchecked, void> > BOOST_MP_LIT(_cppi, Bits)()    \
    {                                                                                                                                                                                                                      \
       using pt = typename boost::multiprecision::literals::detail::make_packed_value_from_str<STR...>::type;                                                                                                              \
-      return boost::multiprecision::literals::detail::make_backend_from_pack<                                                                                                                                             \
-          pt,                                                                                                                                                                                                             \
-          boost::multiprecision::backends::cpp_int_backend<Bits, Bits, boost::multiprecision::signed_magnitude, boost::multiprecision::unchecked, void> >::value;                                                         \
+      using local_backend_type = boost::multiprecision::backends::cpp_int_backend<Bits, Bits, boost::multiprecision::signed_magnitude, boost::multiprecision::unchecked, void>;                                           \
+      auto result { boost::multiprecision::literals::detail::make_backend_from_pack<pt, local_backend_type >::value };                                                                                                    \
+      result.normalize();                                                                                                                                                                                                 \
+      return result;                                                                                                                                                                                                      \
    }                                                                                                                                                                                                                      \
    template <char... STR>                                                                                                                                                                                                 \
    constexpr boost::multiprecision::number<boost::multiprecision::backends::cpp_int_backend<Bits, Bits, boost::multiprecision::unsigned_magnitude, boost::multiprecision::unchecked, void> > BOOST_MP_LIT(_cppui, Bits)() \
    {                                                                                                                                                                                                                      \
       using pt = typename boost::multiprecision::literals::detail::make_packed_value_from_str<STR...>::type;                                                                                                              \
-      return boost::multiprecision::literals::detail::make_backend_from_pack<                                                                                                                                             \
-          pt,                                                                                                                                                                                                             \
-          boost::multiprecision::backends::cpp_int_backend<Bits, Bits, boost::multiprecision::unsigned_magnitude, boost::multiprecision::unchecked, void> >::value;                                                       \
+      using local_backend_type = boost::multiprecision::backends::cpp_int_backend<Bits, Bits, boost::multiprecision::unsigned_magnitude, boost::multiprecision::unchecked, void>;                                         \
+      auto result { boost::multiprecision::literals::detail::make_backend_from_pack<pt, local_backend_type >::value };                                                                                                    \
+      result.normalize();                                                                                                                                                                                                 \
+      return result;                                                                                                                                                                                                      \
    }
 
 BOOST_MP_DEFINE_SIZED_CPP_INT_LITERAL(128)
 BOOST_MP_DEFINE_SIZED_CPP_INT_LITERAL(256)
+BOOST_MP_DEFINE_SIZED_CPP_INT_LITERAL(384)
 BOOST_MP_DEFINE_SIZED_CPP_INT_LITERAL(512)
 BOOST_MP_DEFINE_SIZED_CPP_INT_LITERAL(1024)
 #undef BOOST_MP_LIT
diff --git a/test/Jamfile.v2 b/test/Jamfile.v2
index 1feb0bcc1..a78e60441 100644
--- a/test/Jamfile.v2
+++ b/test/Jamfile.v2
@@ -1283,6 +1283,7 @@ test-suite misc :
       [ run git_issue_734.cpp ]
       [ run git_issue_743.cpp : : : [ check-target-builds ../config//has_float128 : <source>quadmath : <build>no ] ]
       [ run git_issue_759.cpp : : : [ check-target-builds ../config//has_float128 : <source>quadmath : <build>no ] ]
+      [ run git_issue_766.cpp ]
       [ compile git_issue_98.cpp :
          [ check-target-builds ../config//has_float128 : <define>TEST_FLOAT128 <source>quadmath : ]
          [ check-target-builds ../config//has_gmp : <define>TEST_GMP <source>gmp : ]
diff --git a/test/git_issue_766.cpp b/test/git_issue_766.cpp
new file mode 100644
index 000000000..4a4f3662a
--- /dev/null
+++ b/test/git_issue_766.cpp
@@ -0,0 +1,63 @@
+////////////////////////////////////////////////////////////////
+//  Copyright 2026 Christopher Kormanyos.
+//  Distributed under the Boost Software License,
+//  Version 1.0. (See accompanying file LICENSE_1_0.txt
+//  or copy at https://www.boost.org/LICENSE_1_0.txt)
+
+#include <boost/core/lightweight_test.hpp>
+#include <boost/multiprecision/cpp_int.hpp>
+
+namespace Mp = boost::multiprecision;
+using namespace boost::multiprecision::literals;
+
+using uint384_t = Mp::number<Mp::cpp_int_backend<384, 384, Mp::unsigned_magnitude, Mp::unchecked, void>, Mp::et_off>;
+using int512_t = Mp::number<Mp::cpp_int_backend<512, 512, Mp::signed_magnitude, Mp::unchecked, void>, Mp::et_off>;
+
+template <char... TStr>
+constexpr auto operator""_u384() -> uint384_t
+{
+  return operator""_cppui384 < TStr...>();
+}
+
+template <char... TStr>
+constexpr auto operator""_i512() -> int512_t
+{
+  return operator""_cppi512 < TStr...>();
+}
+
+auto main() -> int
+{
+  {
+    constexpr auto value { 0x00000001111111111111111111111111111111111111111111111111111111111111111111111111111111111111_u384 };
+    constexpr auto mask  { 0x0000000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF_u384 };
+
+    constexpr auto masked { value & mask };
+
+    constexpr bool result_mask_is_ok { (value == masked) };
+    constexpr bool result_size_is_ok { (value.backend().size() == masked.backend().size()) };
+
+    static_assert(result_mask_is_ok, "Error: unexpected value results in non-equality");
+    static_assert(result_size_is_ok, "Error: unexpected size results in non-equality");
+
+    BOOST_TEST(result_mask_is_ok);
+    BOOST_TEST(result_size_is_ok);
+  }
+
+  {
+    constexpr auto value { 0x00000001111111111111111111111111111111111111111111111111111111111111111111111111111111111111_i512 };
+    constexpr auto mask  { 0x0000000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF_i512 };
+
+    constexpr auto masked { value & mask };
+
+    constexpr bool result_mask_is_ok { (value == masked) };
+    constexpr bool result_size_is_ok { (value.backend().size() == masked.backend().size()) };
+
+    static_assert(result_mask_is_ok, "Error: unexpected value results in non-equality");
+    static_assert(result_size_is_ok, "Error: unexpected size results in non-equality");
+
+    BOOST_TEST(result_mask_is_ok);
+    BOOST_TEST(result_size_is_ok);
+  }
+
+  return boost::report_errors();
+}