diff --git a/include/nlohmann/detail/input/binary_reader.hpp b/include/nlohmann/detail/input/binary_reader.hpp
index 9085f1cb..d2cf313c 100644
--- a/include/nlohmann/detail/input/binary_reader.hpp
+++ b/include/nlohmann/detail/input/binary_reader.hpp
@@ -2012,7 +2012,7 @@ class binary_reader
                 }
 
                 // get number string
-                std::vector<char_int_type> number_vector;
+                std::vector<char> number_vector;
                 for (std::size_t i = 0; i < size; ++i)
                 {
                     get();
@@ -2020,7 +2020,7 @@ class binary_reader
                     {
                         return false;
                     }
-                    number_vector.push_back(current);
+                    number_vector.push_back(static_cast<char>(current));
                 }
 
                 // parse number string
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index 0d60de15..ba17cadb 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -9512,7 +9512,7 @@ class binary_reader
                 }
 
                 // get number string
-                std::vector<char_int_type> number_vector;
+                std::vector<char> number_vector;
                 for (std::size_t i = 0; i < size; ++i)
                 {
                     get();
@@ -9520,7 +9520,7 @@ class binary_reader
                     {
                         return false;
                     }
-                    number_vector.push_back(current);
+                    number_vector.push_back(static_cast<char>(current));
                 }
 
                 // parse number string