diff --git a/src/actions/transformations/hex_encode.cc b/src/actions/transformations/hex_encode.cc
index 51f30995..4f55d1fe 100644
--- a/src/actions/transformations/hex_encode.cc
+++ b/src/actions/transformations/hex_encode.cc
@@ -41,7 +41,7 @@ std::string HexEncode::evaluate(std::string value,
 
     std::stringstream result;
     for (std::size_t i=0; i < value.length(); i++) {
-        int ii = reinterpret_cast<char>(value[i]);
+        unsigned int ii = (unsigned char)(value[i]);
         result << std::setw(2) << std::setfill('0') << std::hex << ii;
     }