diff --git a/tools/jsonproc/jsonproc.cpp b/tools/jsonproc/jsonproc.cpp
index d58e23eb9..23056a5ff 100755
--- a/tools/jsonproc/jsonproc.cpp
+++ b/tools/jsonproc/jsonproc.cpp
@@ -107,7 +107,7 @@ int main(int argc, char *argv[])
     env.add_callback("cleanString", 1, [](Arguments& args) {
         string badChars = ".'{} \n\t-\u00e9";
         string str = args.at(0)->get<string>();
-        for (uint i = 0; i < str.length(); i++) {
+        for (unsigned int i = 0; i < str.length(); i++) {
             if (badChars.find(str[i]) != std::string::npos) {
                 str[i] = '_';
             }