diff --git a/include/nlohmann/detail/input/input_adapters.hpp b/include/nlohmann/detail/input/input_adapters.hpp
index b7b11de0..9512a771 100644
--- a/include/nlohmann/detail/input/input_adapters.hpp
+++ b/include/nlohmann/detail/input/input_adapters.hpp
@@ -131,9 +131,8 @@ class input_stream_adapter : public input_adapter_protocol
 class input_buffer_adapter : public input_adapter_protocol
 {
   public:
-    JSON_HEDLEY_NON_NULL(2)
     input_buffer_adapter(const char* b, const std::size_t l) noexcept
-        : cursor(b), limit(b + l)
+        : cursor(b), limit(b == nullptr ? nullptr : (b + l))
     {}
 
     // delete because of pointer members
@@ -147,6 +146,7 @@ class input_buffer_adapter : public input_adapter_protocol
     {
         if (JSON_HEDLEY_LIKELY(cursor < limit))
         {
+            assert(cursor != nullptr and limit != nullptr);
             return std::char_traits<char>::to_int_type(*(cursor++));
         }
 
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index 2a32a829..4bbe2707 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -3882,9 +3882,8 @@ class input_stream_adapter : public input_adapter_protocol
 class input_buffer_adapter : public input_adapter_protocol
 {
   public:
-    JSON_HEDLEY_NON_NULL(2)
     input_buffer_adapter(const char* b, const std::size_t l) noexcept
-        : cursor(b), limit(b + l)
+        : cursor(b), limit(b == nullptr ? nullptr : (b + l))
     {}
 
     // delete because of pointer members
@@ -3898,6 +3897,7 @@ class input_buffer_adapter : public input_adapter_protocol
     {
         if (JSON_HEDLEY_LIKELY(cursor < limit))
         {
+            assert(cursor != nullptr and limit != nullptr);
             return std::char_traits<char>::to_int_type(*(cursor++));
         }