diff --git a/src/coders/BasicParser.hpp b/src/coders/BasicParser.hpp
index e0a4445a..3b756f57 100644
--- a/src/coders/BasicParser.hpp
+++ b/src/coders/BasicParser.hpp
@@ -32,7 +32,7 @@ protected:
     void goBack(size_t count = 1);
     void reset();
 
-    int64_t parseSimpleInt(int base);
+    int64_t parseSimpleInt(int base, size_t maxLength = 0xFFFFFFFF);
     dv::value parseNumber(int sign);
     dv::value parseNumber();
     StringT parseString(CharT chr, bool closeRequired = true);
diff --git a/src/coders/BasicParser.inl b/src/coders/BasicParser.inl
index 2e7a3623..7af27fe5 100644
--- a/src/coders/BasicParser.inl
+++ b/src/coders/BasicParser.inl
@@ -349,7 +349,10 @@ std::basic_string<CharT> BasicParser<CharT>::parseXmlName() {
 }
 
 template <typename CharT>
-int64_t BasicParser<CharT>::parseSimpleInt(int base) {
+int64_t BasicParser<CharT>::parseSimpleInt(int base, size_t maxLength) {
+    if (maxLength == 0) return 0;
+
+    size_t start = pos;
     CharT c = peek();
     int index = hexchar2int(c);
     if (index == -1 || index >= base) {
@@ -357,7 +360,7 @@ int64_t BasicParser<CharT>::parseSimpleInt(int base) {
     }
     int64_t value = index;
     pos++;
-    while (hasNext()) {
+    while (hasNext() && pos - start < maxLength) {
         c = source[pos];
         while (c == '_') {
             c = source[++pos];
@@ -476,7 +479,7 @@ std::basic_string<CharT> BasicParser<CharT>::parseString(
                 continue;
             }
             if (c == 'u' || c == 'x') {
-                int codepoint = parseSimpleInt(16);
+                int codepoint = parseSimpleInt(16, c == 'u' ? 4 : 2);
                 ubyte bytes[4];
                 int size = util::encode_utf8(codepoint, bytes);
                 CharT chars[4];
diff --git a/src/graphics/ui/markdown.hpp b/src/graphics/ui/markdown.hpp
index 0f089d58..39b2f1ec 100644
--- a/src/graphics/ui/markdown.hpp
+++ b/src/graphics/ui/markdown.hpp
@@ -22,7 +22,7 @@ namespace markdown {
     Result<wchar_t> process(std::wstring_view source, bool eraseMarkdown);
 
     template <typename CharT>
-    inline std::basic_string<CharT> escape(std::string_view source) {
+    inline std::basic_string<CharT> escape(std::basic_string_view<CharT> source) {
         std::basic_stringstream<CharT> ss;
         int pos = 0;
         while (pos < source.size()) {
diff --git a/src/util/stringutil.cpp b/src/util/stringutil.cpp
index 79f8a1c5..63271a13 100644
--- a/src/util/stringutil.cpp
+++ b/src/util/stringutil.cpp
@@ -40,7 +40,7 @@ std::string util::escape(std::string_view s, bool escapeUnicode) {
                     uint cpsize;
                     int codepoint = decode_utf8(cpsize, s.data() + pos);
                     if (escapeUnicode) {
-                        ss << "\\u" << std::hex << codepoint;
+                        ss << "\\u" << std::setw(4) << std::setfill('0') << std::hex << codepoint;
                     } else {
                         ss << std::string(s.data() + pos, cpsize);
                     }
diff --git a/test/util/stringutil.cpp b/test/util/stringutil.cpp
index fd459663..22df2b35 100644
--- a/test/util/stringutil.cpp
+++ b/test/util/stringutil.cpp
@@ -1,4 +1,5 @@
 #include "util/stringutil.hpp"
+#include "coders/BasicParser.hpp"
 
 #include <gtest/gtest.h>
 
@@ -16,6 +17,25 @@ TEST(stringutil, utf8) {
     EXPECT_EQ(str, str2);
 }
 
+static std::wstring gen_random_unicode_wstring(int n) {
+    std::wstring str;
+    str.resize(n);
+    for (int i = 0; i < n; i++) {
+        // wstring is 16 bit in some systems
+        str[i] = rand() & 0xFFFF;
+    }
+    return str;
+}
+
+TEST(stringutil, utf8_random) {
+    srand(5436324);
+
+    auto str = gen_random_unicode_wstring(10'000);
+    auto utf8str = util::wstr2str_utf8(str);
+    auto back = util::str2wstr_utf8(utf8str);
+    EXPECT_EQ(str, back);
+}
+
 TEST(stringutil, base64) {
     srand(2019);
     for (size_t size = 0; size < 30; size++) {
@@ -47,3 +67,37 @@ TEST(stringutil, base64_urlsafe) {
         }
     }
 }
+
+class StringParser : BasicParser<char> {
+public:
+    StringParser(std::string_view source) : BasicParser("<string>", source) {}
+
+    std::string parse() {
+        ++pos;
+        return parseString(source[0], true);
+    }
+};
+
+TEST(stringutil, escape_cases) {
+    auto escaped = util::escape("тест5", true);
+    auto expected = "\"\\u0442\\u0435\\u0441\\u04425\"";
+    ASSERT_EQ(expected, escaped);
+
+    srand(345873458);
+    for (int i = 0; i < 36; i++) {
+        rand();
+    }
+
+    auto str = gen_random_unicode_wstring(40);
+    auto utf8str = util::wstr2str_utf8(str);
+    escaped = util::escape(utf8str, true);
+
+    StringParser parser(escaped);
+    auto restored = parser.parse();
+    for (int i = 0; i < utf8str.length(); i++) {
+        if (utf8str[i] != restored[i]) {
+            std::cout << i << ": " << (int)utf8str[i] << " " << (int)restored[i] << std::endl;
+        }
+    }
+    EXPECT_EQ(utf8str, restored);
+}