diff --git a/src/util/str_util.cpp b/src/util/str_util.cpp
index e0d8bfeb..259e7900 100644
--- a/src/util/str_util.cpp
+++ b/src/util/str_util.cpp
@@ -30,7 +30,7 @@ std::string base64_encode(const std::string &in)
     return out;
 }
 
-static char T[256] = { 0 };
+static int T[256] = { 0 };
 
 std::string base64_decode(const std::string &in)
 {