diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index 93bb4f23..7900cf96 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -10135,7 +10135,7 @@ class serializer
             return;
         }
 
-        const bool is_negative = (x <= 0) and (x != 0);  // see issue #755
+        const bool is_negative = not (x >= 0);  // see issue #755
         std::size_t i = 0;
 
         while (x != 0)