diff --git a/include/nlohmann/detail/input/input_adapters.hpp b/include/nlohmann/detail/input/input_adapters.hpp
index bc1340a02..05fd4c816 100644
--- a/include/nlohmann/detail/input/input_adapters.hpp
+++ b/include/nlohmann/detail/input/input_adapters.hpp
@@ -109,7 +109,8 @@ class token_carry_buffer
     void append(const char* first, const char* last)
     {
         const auto n = static_cast<std::size_t>(last - first);
-        if (n > static_cast<std::size_t>(m_capacity_end - m_end))
+        const auto room = static_cast<std::size_t>(m_capacity_end - m_end);
+        if (n > room)
         {
             grow(n);
         }
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index aea492e55..51661ab17 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -8574,7 +8574,8 @@ class token_carry_buffer
     void append(const char* first, const char* last)
     {
         const auto n = static_cast<std::size_t>(last - first);
-        if (n > static_cast<std::size_t>(m_capacity_end - m_end))
+        const auto room = static_cast<std::size_t>(m_capacity_end - m_end);
+        if (n > room)
         {
             grow(n);
         }