diff --git a/tests/parse_test.cpp b/tests/parse_test.cpp
index 2691690..3bc01f9 100644
--- a/tests/parse_test.cpp
+++ b/tests/parse_test.cpp
@@ -121,15 +121,15 @@ int main() {
   assert(hash("tesT") == hash("test"));
   assert(hash("test") != hash("tset"));
 
-  auto percent_decoded = "testing æøå !#$&'()*+,/:;=?@[]123";
-  auto percent_encoded = "testing+æøå+%21%23%24%26%27%28%29%2A%2B%2C%2F%3A%3B%3D%3F%40%5B%5D123";
+  auto percent_decoded = "testing æøå !#$&'()*+,/:;=?@[]123-._~\r\n";
+  auto percent_encoded = "testing%20%C3%A6%C3%B8%C3%A5%20%21%23%24%26%27%28%29%2A%2B%2C%2F%3A%3B%3D%3F%40%5B%5D123-._~%0D%0A";
   assert(Percent::encode(percent_decoded) == percent_encoded);
   assert(Percent::decode(percent_encoded) == percent_decoded);
   assert(Percent::decode(Percent::encode(percent_decoded)) == percent_decoded);
 
   SimpleWeb::CaseInsensitiveMultimap fields = {{"test1", "æøå"}, {"test2", "!#$&'()*+,/:;=?@[]"}};
-  auto query_string1 = "test1=æøå&test2=%21%23%24%26%27%28%29%2A%2B%2C%2F%3A%3B%3D%3F%40%5B%5D";
-  auto query_string2 = "test2=%21%23%24%26%27%28%29%2A%2B%2C%2F%3A%3B%3D%3F%40%5B%5D&test1=æøå";
+  auto query_string1 = "test1=%C3%A6%C3%B8%C3%A5&test2=%21%23%24%26%27%28%29%2A%2B%2C%2F%3A%3B%3D%3F%40%5B%5D";
+  auto query_string2 = "test2=%21%23%24%26%27%28%29%2A%2B%2C%2F%3A%3B%3D%3F%40%5B%5D&test1=%C3%A6%C3%B8%C3%A5";
   auto query_string_result = QueryString::create(fields);
   assert(query_string_result == query_string1 || query_string_result == query_string2);
   auto fields_result1 = QueryString::parse(query_string1);
diff --git a/utility.hpp b/utility.hpp
index dfb7004..76fc7d5 100644
--- a/utility.hpp
+++ b/utility.hpp
@@ -46,10 +46,8 @@ namespace SimpleWeb {
       result.reserve(value.size()); // Minimum size of result
 
       for(auto &chr : value) {
-        if(chr == ' ')
-          result += '+';
-        else if(chr == '!' || chr == '#' || chr == '$' || (chr >= '&' && chr <= ',') || chr == '/' || chr == ':' || chr == ';' || chr == '=' || chr == '?' || chr == '@' || chr == '[' || chr == ']')
-          result += std::string("%") + hex_chars[chr >> 4] + hex_chars[chr & 15];
+        if(!((chr >= '0' && chr <= '9') || (chr >= 'A' && chr <= 'Z') || (chr >= 'a' && chr <= 'z') || chr == '-' || chr == '.' || chr == '_' || chr == '~'))
+          result += std::string("%") + hex_chars[static_cast<unsigned char>(chr) >> 4] + hex_chars[static_cast<unsigned char>(chr) & 15];
         else
           result += chr;
       }