diff --git a/src/util/format/builder.cpp b/src/util/format/builder.cpp
index 5b31f7e..5bff2ab 100644
--- a/src/util/format/builder.cpp
+++ b/src/util/format/builder.cpp
@@ -6,6 +6,7 @@
 
 #include <algorithm> // min
 #include <cstddef>   // size_t
+#include <cstdint>   // uint8_t, uint16_t, uint32_t, uint64_t
 #include <iomanip>   // setprecision
 #include <ios>       // defaultfloat, fixed
 #include <limits>    // numeric_limits
@@ -28,9 +29,42 @@ void Builder::putLiteral(std::string_view literal)
 	}
 }
 
-void Builder::putU64(size_t value, char fill, Align align, Sign sign, bool zeroPadding, size_t width, bool isNegative) const
+static constexpr std::string numberToString(size_t value, uint8_t base, bool uppercase)
 {
-	std::string string = (std::stringstream {} << value).str();
+	std::string result;
+
+	if (value > std::numeric_limits<uint32_t>::max()) {
+		result.reserve(64);
+	}
+	else if (value > std::numeric_limits<uint16_t>::max()) {
+		result.reserve(32);
+	}
+
+	constexpr const auto& lookupLowercase = "0123456789abcdef";
+	constexpr const auto& lookupUppercase = "0123456789ABCDEF";
+
+	if (value == 0) {
+		result = '0';
+	}
+	else if (uppercase) {
+		while (value > 0) {
+			result.insert(0, 1, lookupUppercase[value % base]);
+			value /= base;
+		}
+	}
+	else {
+		while (value > 0) {
+			result.insert(0, 1, lookupLowercase[value % base]);
+			value /= base;
+		}
+	}
+
+	return result;
+}
+
+void Builder::putU64(size_t value, uint8_t base, bool uppercase, char fill, Align align, Sign sign, bool zeroPadding, size_t width, bool isNegative) const
+{
+	std::string string = numberToString(value, base, uppercase);
 
 	// Sign
 	std::string signCharacter = "";
@@ -96,11 +130,11 @@ void Builder::putU64(size_t value, char fill, Align align, Sign sign, bool zeroP
 	};
 }
 
-void Builder::putI64(int64_t value, char fill, Align align, Sign sign, bool zeroPadding, size_t width) const
+void Builder::putI64(int64_t value, uint8_t base, bool uppercase, char fill, Align align, Sign sign, bool zeroPadding, size_t width) const
 {
 	bool isNegative = value < 0;
 	value = isNegative ? -value : value;
-	putU64(static_cast<uint64_t>(value), fill, align, sign, zeroPadding, width, isNegative);
+	putU64(static_cast<uint64_t>(value), base, uppercase, fill, align, sign, zeroPadding, width, isNegative);
 }
 
 void Builder::putF64(double number, uint8_t precision) const
diff --git a/src/util/format/builder.h b/src/util/format/builder.h
index 5e3745b..c03afc6 100644
--- a/src/util/format/builder.h
+++ b/src/util/format/builder.h
@@ -36,8 +36,8 @@ public:
 
 	void putLiteral(std::string_view literal);
 
-	void putU64(size_t value, char fill = ' ', Align align = Align::Right, Sign sign = Sign::Negative, bool zeroPadding = false, size_t width = 0, bool isNegative = false) const;
-	void putI64(int64_t value, char fill = ' ', Align align = Align::Right, Sign sign = Sign::Negative, bool zeroPadding = false, size_t width = 0) const;
+	void putU64(size_t value, uint8_t base = 10, bool uppercase = false, char fill = ' ', Align align = Align::Right, Sign sign = Sign::Negative, bool zeroPadding = false, size_t width = 0, bool isNegative = false) const;
+	void putI64(int64_t value, uint8_t base = 10, bool uppercase = false, char fill = ' ', Align align = Align::Right, Sign sign = Sign::Negative, bool zeroPadding = false, size_t width = 0) const;
 	void putF64(double number, uint8_t precision = 6) const;
 	void putCharacter(char character) const { m_builder.write(&character, 1); }
 	void putString(std::string_view string, char fill = ' ', Align align = Align::Left, size_t width = 0) const;
diff --git a/src/util/format/formatter.h b/src/util/format/formatter.h
index 6b8bc75..f30702a 100644
--- a/src/util/format/formatter.h
+++ b/src/util/format/formatter.h
@@ -6,6 +6,7 @@
 
 #pragma once
 
+#include <cassert>
 #include <cstddef> // size_t
 #include <cstdint> // int8_t, int32_t, int64_t, uint8_t, uint32_t
 #include <map>
@@ -91,14 +92,38 @@ struct Formatter<T> {
 
 	void format(Builder& builder, T value) const
 	{
-		if (std::is_signed_v<T>) {
-			builder.putI64(
-				value, specifier.fill, specifier.align, specifier.sign,
+		uint8_t base = 0;
+		bool uppercase = false;
+		switch (specifier.type) {
+		case PresentationType::BinaryUppercase:
+			uppercase = true;
+		case PresentationType::Binary:
+			base = 2;
+			break;
+		case PresentationType::Octal:
+			base = 8;
+			break;
+		case PresentationType::None:
+		case PresentationType::Decimal:
+			base = 10;
+			break;
+		case PresentationType::HexUppercase:
+			uppercase = true;
+		case PresentationType::Hex:
+			base = 16;
+			break;
+		default:
+			assert(false);
+		};
+
+		if constexpr (std::is_unsigned_v<T>) {
+			builder.putU64(
+				value, base, uppercase, specifier.fill, specifier.align, specifier.sign,
 				specifier.zeroPadding, specifier.width);
 		}
-		if (std::is_unsigned_v<T>) {
-			builder.putU64(
-				value, specifier.fill, specifier.align, specifier.sign,
+		else {
+			builder.putI64(
+				value, base, uppercase, specifier.fill, specifier.align, specifier.sign,
 				specifier.zeroPadding, specifier.width);
 		}
 	}