1 files changed, 15 insertions, 1 deletions
diff --git a/boost/multiprecision/cpp_int/divide.hpp b/boost/multiprecision/cpp_int/divide.hpp
index c94bc71498..5fe6ce6ad8 100644
--- a/boost/multiprecision/cpp_int/divide.hpp
+++ b/boost/multiprecision/cpp_int/divide.hpp
@@ -242,7 +242,21 @@ void divide_unsigned_helper(
       // Update r in a way that won't actually produce a negative result
       // in case the argument types are unsigned:
       //
-      if(r.compare(t) > 0)
+      if(truncated_t && carry)
+      {
+         // We need to calculate 2^n + t - r
+         // where n is the number of bits in this type.
+         // Simplest way is to get 2^n - r by complementing
+         // r, then add t to it.  Note that we can't call eval_complement
+         // in case this is a signed checked type:
+         for(unsigned i = 0; i <= r_order; ++i)
+            r.limbs()[i] = ~prem[i];
+         r.normalize();
+         eval_increment(r);
+         eval_add(r, t);
+         r_neg = !r_neg;
+      }
+      else if(r.compare(t) > 0)
       {
          eval_subtract(r, t);
       }