diff --git a/include/boost/url/rfc/detail/paths_bnf.hpp b/include/boost/url/rfc/detail/paths_bnf.hpp
index 68e6571b..a011ba3f 100644
--- a/include/boost/url/rfc/detail/paths_bnf.hpp
+++ b/include/boost/url/rfc/detail/paths_bnf.hpp
@@ -35,7 +35,8 @@ struct segment_bnf
         using bnf::parse;
         return parse(it, end, ec,
             pct_encoded_bnf<
-                pchar_mask>{t.v});
+                masked_char_set<
+                    pchar_mask>>{t.v});
     }
 };
 
@@ -57,7 +58,8 @@ struct segment_nz_bnf
         auto const start = it;
         if(! parse(it, end, ec,
             pct_encoded_bnf<
-                pchar_mask>{t.v}))
+                masked_char_set<
+                pchar_mask>>{t.v}))
             return false;
         if(it == start)
         {
@@ -87,8 +89,9 @@ struct segment_nz_nc_bnf
         auto const start = it;
         if(! parse(it, end, ec,
             pct_encoded_bnf<
-                pchar_mask &
-                ~colon_char_mask>{t.v}))
+                masked_char_set<
+                    pchar_mask &
+                    ~colon_char_mask>>{t.v}))
             return false;
         if(it == start)
         {
diff --git a/include/boost/url/rfc/detail/query_params_bnf.hpp b/include/boost/url/rfc/detail/query_params_bnf.hpp
index c412f34e..5c114fd1 100644
--- a/include/boost/url/rfc/detail/query_params_bnf.hpp
+++ b/include/boost/url/rfc/detail/query_params_bnf.hpp
@@ -33,7 +33,8 @@ struct query_params_bnf
         // key
         if(! parse(it, end, ec,
             pct_encoded_bnf<
-                qpchar_mask>{t.key}))
+                masked_char_set<
+                    qpchar_mask>>{t.key}))
             return false;
         // "="
         if(! parse(it, end, ec, '='))
@@ -47,8 +48,9 @@ struct query_params_bnf
         t.value.emplace();
         if(! parse(it, end, ec,
             pct_encoded_bnf<
-                qpchar_mask |
-                equals_char_mask>{*t.value}))
+                masked_char_set<
+                    qpchar_mask |
+                    equals_char_mask>>{*t.value}))
         {
             ec = {};
             t.value.reset();
@@ -75,7 +77,8 @@ struct query_params_bnf
         // key
         if(! parse(it, end, ec,
             pct_encoded_bnf<
-                qpchar_mask>{t.key}))
+                masked_char_set<
+                    qpchar_mask>>{t.key}))
             return false;
         // "="
         if(! parse(it, end, ec, '='))
@@ -89,8 +92,10 @@ struct query_params_bnf
         t.value.emplace();
         if(! parse(it, end, ec,
             pct_encoded_bnf<
-                qpchar_mask |
-                equals_char_mask>{*t.value}))
+                masked_char_set<
+                    qpchar_mask |
+                    equals_char_mask>>{
+                        *t.value}))
         {
             ec = {};
             t.value.reset();
diff --git a/include/boost/url/rfc/impl/fragment_bnf.ipp b/include/boost/url/rfc/impl/fragment_bnf.ipp
index 5b9da82a..954f1299 100644
--- a/include/boost/url/rfc/impl/fragment_bnf.ipp
+++ b/include/boost/url/rfc/impl/fragment_bnf.ipp
@@ -28,9 +28,10 @@ parse(
     using bnf::parse;
     return parse(it, end, ec,
         pct_encoded_bnf<
-            pchar_mask |
-            slash_char_mask |
-            question_char_mask>{t.v});
+            masked_char_set<
+                pchar_mask |
+                slash_char_mask |
+                question_char_mask>>{t.v});
 }
 
 } // urls
diff --git a/include/boost/url/rfc/impl/host_bnf.ipp b/include/boost/url/rfc/impl/host_bnf.ipp
index 501e22b4..1853c841 100644
--- a/include/boost/url/rfc/impl/host_bnf.ipp
+++ b/include/boost/url/rfc/impl/host_bnf.ipp
@@ -73,8 +73,9 @@ parse(
         pct_encoded_str ns;
         if(! parse(it, end, ec,
             pct_encoded_bnf<
-                unsub_char_mask>{
-                    t.name_}))
+                masked_char_set<
+                    unsub_char_mask>>{
+                        t.name_}))
         {
             // bad reg-name
             return false;
diff --git a/include/boost/url/rfc/impl/pct_encoded_bnf.hpp b/include/boost/url/rfc/impl/pct_encoded_bnf.hpp
index 77979216..b0d19e65 100644
--- a/include/boost/url/rfc/impl/pct_encoded_bnf.hpp
+++ b/include/boost/url/rfc/impl/pct_encoded_bnf.hpp
@@ -16,19 +16,18 @@
 namespace boost {
 namespace urls {
 
-template<std::uint8_t CharMask>
+template<class CharSet>
 bool
 parse(
     char const*& it,
     char const* const end,
     error_code& ec,
     pct_encoded_bnf<
-        CharMask> const& t) noexcept
+        CharSet> const& t) noexcept
 {
     auto const start = it;
-    masked_char_set<CharMask> cs;
     if(! detail::parse_pct_encoded_impl(
-        it, end, ec, cs,
+        it, end, ec, CharSet{},
             t.v.decoded_size))
         return false;
     t.v.str = string_view(
diff --git a/include/boost/url/rfc/impl/userinfo_bnf.ipp b/include/boost/url/rfc/impl/userinfo_bnf.ipp
index 27af1b0f..e682fd1c 100644
--- a/include/boost/url/rfc/impl/userinfo_bnf.ipp
+++ b/include/boost/url/rfc/impl/userinfo_bnf.ipp
@@ -36,11 +36,13 @@ parse(
         bnf::literal<':'>> colon;
     if(! parse(it, end, ec,
         pct_encoded_bnf<
-            unsub_char_mask>{user},
+            masked_char_set<
+                unsub_char_mask>>{user},
         colon,
         pct_encoded_bnf<
-            unsub_char_mask |
-            colon_char_mask>{pass}))
+            masked_char_set<
+                unsub_char_mask |
+                colon_char_mask>>{pass}))
         return false;
     t.str = string_view(
         start, it - start);
diff --git a/include/boost/url/rfc/pct_encoded_bnf.hpp b/include/boost/url/rfc/pct_encoded_bnf.hpp
index c4e8ec97..1eb93a60 100644
--- a/include/boost/url/rfc/pct_encoded_bnf.hpp
+++ b/include/boost/url/rfc/pct_encoded_bnf.hpp
@@ -13,6 +13,8 @@
 #include <boost/url/detail/config.hpp>
 #include <boost/url/error.hpp>
 #include <boost/url/string.hpp>
+#include <boost/url/bnf/detail/char_set.hpp>
+#include <boost/static_assert.hpp>
 
 namespace boost {
 namespace urls {
@@ -35,21 +37,25 @@ struct pct_encoded_str
     @see
         https://datatracker.ietf.org/doc/html/rfc3986#section-2.1
 */
-template<std::uint8_t CharMask>
+template<class CharSet>
 struct pct_encoded_bnf
 {
     pct_encoded_str& v;
 
-    template<std::uint8_t CharMask_>
+    BOOST_STATIC_ASSERT(
+        bnf::detail::is_char_set_pred<
+            CharSet>::value);
+
+    template<class CharSet_>
     friend
     bool
     parse(
         char const*& it,
         char const* const end,
         error_code& ec,
-        pct_encoded_bnf<CharMask_> const& t) noexcept;
+        pct_encoded_bnf<CharSet_> const& t) noexcept;
 };
-    
+
 } // urls
 } // boost