diff --git a/src/modules/_Roxen/testsuite.in b/src/modules/_Roxen/testsuite.in
index 1733c9839cb4ae953714842cc30ab173e957660e..6b723ea106129f3557e85d9430b0471237f8d82e 100644
--- a/src/modules/_Roxen/testsuite.in
+++ b/src/modules/_Roxen/testsuite.in
@@ -8,6 +8,7 @@ test_eq(_Roxen.html_encode_string("a&b<c>d"), "a&amp;b&lt;c&gt;d")
 test_eq(_Roxen.http_decode_string(""), "")
 test_eq(_Roxen.http_decode_string("abc+d%20e%41"), "abc+d eA")
 test_eq(_Roxen.http_decode_string(""), "")
+test_eq(_Roxen.http_decode_string("+"), "+")
 test_do(_Roxen.http_decode_string("%"))
 test_do(_Roxen.http_decode_string("%0"))
 test_do(_Roxen.http_decode_string("%%"))