diff --git a/include/mapnik/expression_grammar_x3_def.hpp b/include/mapnik/expression_grammar_x3_def.hpp
index f468b5904..a7efe6173 100644
--- a/include/mapnik/expression_grammar_x3_def.hpp
+++ b/include/mapnik/expression_grammar_x3_def.hpp
@@ -67,7 +67,7 @@ namespace mapnik { namespace grammar {
     x3::uint_parser<char, 16, 2, 2> const hex2 {};
 
     namespace {
-    auto const& escaped = json::grammar::escaped;
+    auto const& escaped_unicode = json::grammar::escaped_unicode;
     }
 
     auto append = [](auto const& ctx)
@@ -315,12 +315,14 @@ namespace mapnik { namespace grammar {
     auto const single_quoted_string = x3::rule<class single_quoted_string, std::string> {} = lit('\'')
         >> no_skip[*(unesc_char[append]
                      |
+                     //(lit('\\') > escaped_unicode[append]) // FIXME (!)
+                     //|
                      (~char_('\''))[append])] > lit('\'');
 
     auto const double_quoted_string = x3::rule<class double_quoted_string, std::string> {} = lit('"')
         >> no_skip[*(unesc_char[append]
                      |
-                     escaped[append]
+                     (lit('\\') > escaped_unicode[append])
                      |
                      (~char_('"'))[append])] > lit('"');
 
diff --git a/include/mapnik/json/unicode_string_grammar_x3_def.hpp b/include/mapnik/json/unicode_string_grammar_x3_def.hpp
index 43d40c9aa..fd0bcebe1 100644
--- a/include/mapnik/json/unicode_string_grammar_x3_def.hpp
+++ b/include/mapnik/json/unicode_string_grammar_x3_def.hpp
@@ -112,26 +112,28 @@ x3::uint_parser<uchar, 16, 8, 8> const hex8 {};
 unicode_string_grammar_type const unicode_string("Unicode String");
 // rules
 x3::rule<class double_quoted_tag, std::string> const double_quoted("Double-quoted string");
-x3::rule<class escaped_tag, std::string> const escaped("Escaped Characted");
+x3::rule<class escaped_tag, std::string> const escaped("Escaped Character");
+x3::rule<class escaped_unicode_tag, std::string> const escaped_unicode("Escaped Unicode code point(s)");
 x3::rule<class utf16_string_tag, std::vector<std::uint16_t>> const utf16_string("UTF16 encoded string");
 
 auto unicode_string_def = double_quoted
     ;
-
-auto utf16_string_def = lit('u') > hex4 > *(lit("\\u") > hex4);
-
+auto utf16_string_def = lit('u') > hex4 > *(lit("\\u") > hex4)
+    ;
+auto escaped_unicode_def =
+    (lit('x') > hex2[push_char])
+    |
+    utf16_string[push_utf16]
+    |
+    (lit('U') > hex8[push_utf8])
+    ;
 auto const escaped_def = lit('\\') >
-    ((lit('x') > hex2[push_char])
-     |
-     utf16_string[push_utf16]
-     |
-     (lit('U') > hex8[push_utf8])
+    (escaped_unicode[append]
      |
      char_("0abtnvfre\"/\\N_LP \t")[push_esc]
      |
      eol) // continue to next line
     ;
-
 auto const double_quoted_def = lit('"') > no_skip[*(escaped[append] | (~char_('"'))[append])] > lit('"');
 
 #pragma GCC diagnostic push
@@ -141,6 +143,7 @@ BOOST_SPIRIT_DEFINE(
     unicode_string,
     double_quoted,
     escaped,
+    escaped_unicode,
     utf16_string
     );