diff --git a/include/nlohmann/detail/output/serializer.hpp b/include/nlohmann/detail/output/serializer.hpp
index 84a9c370d..8650694c0 100644
--- a/include/nlohmann/detail/output/serializer.hpp
+++ b/include/nlohmann/detail/output/serializer.hpp
@@ -850,11 +850,16 @@ class serializer
                 // for the scan. Without it, text whose characters all have to be
                 // escaped - CJK under ensure_ascii, where every byte is >= 0x80 -
                 // runs the scanner once per character only to be told zero.
-                const std::size_t run = EnsureAscii
-                                        ? (is_ascii_copyable(data[i])
-                                           ? find_ascii_copyable_run(data + i, s.size() - i)
-                                           : 0)
-                                        : string_bulk_run(data + i, s.size() - i);
+                const std::size_t run = [&]() -> std::size_t
+                {
+                    if (EnsureAscii)
+                    {
+                        return is_ascii_copyable(data[i])
+                        ? find_ascii_copyable_run(data + i, s.size() - i)
+                        : 0;
+                    }
+                    return string_bulk_run(data + i, s.size() - i);
+                }();
                 if (run != 0)
                 {
                     // emit any bytes still pending in string_buffer first to
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index 0d99e22ab..4d1911295 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -21910,11 +21910,16 @@ class serializer
                 // for the scan. Without it, text whose characters all have to be
                 // escaped - CJK under ensure_ascii, where every byte is >= 0x80 -
                 // runs the scanner once per character only to be told zero.
-                const std::size_t run = EnsureAscii
-                                        ? (is_ascii_copyable(data[i])
-                                           ? find_ascii_copyable_run(data + i, s.size() - i)
-                                           : 0)
-                                        : string_bulk_run(data + i, s.size() - i);
+                const std::size_t run = [&]() -> std::size_t
+                {
+                    if (EnsureAscii)
+                    {
+                        return is_ascii_copyable(data[i])
+                        ? find_ascii_copyable_run(data + i, s.size() - i)
+                        : 0;
+                    }
+                    return string_bulk_run(data + i, s.size() - i);
+                }();
                 if (run != 0)
                 {
                     // emit any bytes still pending in string_buffer first to