diff --git a/CHANGELOG.md b/CHANGELOG.md
index 76bba8a..33d50eb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,10 @@ options. The project adheres to semantic versioning.
 
 * Allow integers to have leading zeroes.
 
+### Bug Fixes
+
+* Fix a warning about possible loss of data.
+
 ## 2.1.1
 
 ### Bug Fixes
diff --git a/include/cxxopts.hpp b/include/cxxopts.hpp
index 206e1c7..f590587 100644
--- a/include/cxxopts.hpp
+++ b/include/cxxopts.hpp
@@ -547,7 +547,7 @@ namespace cxxopts
 
       for (auto iter = value_match.first; iter != value_match.second; ++iter)
       {
-        size_t digit = 0;
+        US digit = 0;
 
         if (*iter >= '0' && *iter <= '9')
         {