diff --git a/src/tools/stringTools.cpp b/src/tools/stringTools.cpp
index dcd5fc4ff..8e81d1cf1 100644
--- a/src/tools/stringTools.cpp
+++ b/src/tools/stringTools.cpp
@@ -241,7 +241,8 @@ std::string kiwix::urlEncode(const std::string& value, bool encodeReserved)
     if (!needsEscape(*it, encodeReserved)) {
       os << *it;
     } else {
-      os << '%' << std::setw(2) << static_cast<unsigned int>(static_cast<unsigned char>(*it));
+      const unsigned int charVal = static_cast<unsigned char>(*it);
+      os << '%' << std::setw(2) << std::setfill('0') << charVal;
     }
   }
   return os.str();
diff --git a/test/stringTools.cpp b/test/stringTools.cpp
index b6965f8fb..252264412 100644
--- a/test/stringTools.cpp
+++ b/test/stringTools.cpp
@@ -141,8 +141,7 @@ TEST(stringTools, urlEncode)
   EXPECT_EQ(urlEncode(otherSymbols), "%60%23%25%5E%5B%5D%7B%7D%5C%7C%22%3C%3E");
   EXPECT_EQ(urlEncode(otherSymbols), urlEncode(otherSymbols, true));
 
-  // XXX: there is a bug with formatting of single-digit hex values
-  EXPECT_EQ(urlEncode(whitespace), "%20% A% 9% D");
+  EXPECT_EQ(urlEncode(whitespace), "%20%0A%09%0D");
   EXPECT_EQ(urlEncode(whitespace), urlEncode(whitespace, true));
 
   EXPECT_EQ(urlEncode(someNonASCIIChars), "%CE%A3%E2%99%82%E2%99%80%E3%83%84");