diff --git a/include/nlohmann/detail/output/serializer.hpp b/include/nlohmann/detail/output/serializer.hpp
index e6811ceb3b..703a69e44c 100644
--- a/include/nlohmann/detail/output/serializer.hpp
+++ b/include/nlohmann/detail/output/serializer.hpp
@@ -630,7 +630,7 @@ class serializer
         if (is_negative)
         {
             *buffer_ptr = '-';
-            abs_value = static_cast<number_unsigned_t>(std::abs(static_cast<std::intmax_t>(x)));
+            abs_value = remove_sign(x);
 
             // account one more byte for the minus sign
             n_chars = 1 + count_digits(abs_value);
@@ -811,6 +811,17 @@ class serializer
         return state;
     }
 
+    inline number_unsigned_t remove_sign(number_unsigned_t x) noexcept
+    {
+        return x;
+    }
+
+    inline number_unsigned_t remove_sign(number_integer_t x) noexcept
+    {
+        assert(x < std::numeric_limits<number_integer_t>::max());
+        return static_cast<number_unsigned_t>(-(x + 1)) + 1;
+    }
+
   private:
     /// the output of the serializer
     output_adapter_t<char> o = nullptr;
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index 2a32a82963..ae0d5fd5b0 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -14264,7 +14264,7 @@ class serializer
         if (is_negative)
         {
             *buffer_ptr = '-';
-            abs_value = static_cast<number_unsigned_t>(std::abs(static_cast<std::intmax_t>(x)));
+            abs_value = remove_sign(x);
 
             // account one more byte for the minus sign
             n_chars = 1 + count_digits(abs_value);
@@ -14445,6 +14445,17 @@ class serializer
         return state;
     }
 
+    inline number_unsigned_t remove_sign(number_unsigned_t x) noexcept
+    {
+        return x;
+    }
+
+    inline number_unsigned_t remove_sign(number_integer_t x) noexcept
+    {
+        assert(x < std::numeric_limits<number_integer_t>::max());
+        return static_cast<number_unsigned_t>(-(x + 1)) + 1;
+    }
+
   private:
     /// the output of the serializer
     output_adapter_t<char> o = nullptr;