diff --git a/Tests/LibC/TestSnprintf.cpp b/Tests/LibC/TestSnprintf.cpp
index 2eca2d52b3..7346200922 100644
--- a/Tests/LibC/TestSnprintf.cpp
+++ b/Tests/LibC/TestSnprintf.cpp
@@ -14,11 +14,12 @@
 
 #pragma GCC diagnostic ignored "-Wformat-nonliteral"
 
+template<typename TArg>
 struct Testcase {
     const char* dest;
     size_t dest_n;
     const char* fmt;
-    const char* arg;
+    const TArg arg;
     int expected_return;
     const char* dest_expected;
     size_t dest_expected_n; // == dest_n
@@ -42,7 +43,8 @@ static String show(const ByteBuffer& buf)
     return builder.build();
 }
 
-static bool test_single(const Testcase& testcase)
+template<typename TArg>
+static bool test_single(const Testcase<TArg>& testcase)
 {
     constexpr size_t SANDBOX_CANARY_SIZE = 8;
 
@@ -109,35 +111,155 @@ static const char* const POISON = (const char*)1;
 
 TEST_CASE(golden_path)
 {
-    EXPECT(test_single({ LITERAL("Hello World!\0\0\0"), "Hello Friend!", POISON, 13, LITERAL("Hello Friend!\0\0") }));
-    EXPECT(test_single({ LITERAL("Hello World!\0\0\0"), "Hello %s!", "Friend", 13, LITERAL("Hello Friend!\0\0") }));
-    EXPECT(test_single({ LITERAL("aaaaaaaaaa"), "whf", POISON, 3, LITERAL("whf\0aaaaaa") }));
-    EXPECT(test_single({ LITERAL("aaaaaaaaaa"), "w%sf", "h", 3, LITERAL("whf\0aaaaaa") }));
+    EXPECT(test_single<const char*>({ LITERAL("Hello World!\0\0\0"), "Hello Friend!", POISON, 13, LITERAL("Hello Friend!\0\0") }));
+    EXPECT(test_single<const char*>({ LITERAL("Hello World!\0\0\0"), "Hello %s!", "Friend", 13, LITERAL("Hello Friend!\0\0") }));
+    EXPECT(test_single<const char*>({ LITERAL("aaaaaaaaaa"), "whf", POISON, 3, LITERAL("whf\0aaaaaa") }));
+    EXPECT(test_single<const char*>({ LITERAL("aaaaaaaaaa"), "w%sf", "h", 3, LITERAL("whf\0aaaaaa") }));
 }
 
 TEST_CASE(border_cases)
 {
-    EXPECT(test_single({ LITERAL("Hello World!\0\0"), "Hello Friend!", POISON, 13, LITERAL("Hello Friend!\0") }));
-    EXPECT(test_single({ LITERAL("AAAA"), "whf", POISON, 3, LITERAL("whf\0") }));
-    EXPECT(test_single({ LITERAL("AAAA"), "%s", "whf", 3, LITERAL("whf\0") }));
+    EXPECT(test_single<const char*>({ LITERAL("Hello World!\0\0"), "Hello Friend!", POISON, 13, LITERAL("Hello Friend!\0") }));
+    EXPECT(test_single<const char*>({ LITERAL("AAAA"), "whf", POISON, 3, LITERAL("whf\0") }));
+    EXPECT(test_single<const char*>({ LITERAL("AAAA"), "%s", "whf", 3, LITERAL("whf\0") }));
 }
 
 TEST_CASE(too_long)
 {
-    EXPECT(test_single({ LITERAL("Hello World!\0"), "Hello Friend!", POISON, 13, LITERAL("Hello Friend\0") }));
-    EXPECT(test_single({ LITERAL("Hello World!\0"), "This source is %s too long!", "just *way*", 35, LITERAL("This source \0") }));
-    EXPECT(test_single({ LITERAL("x"), "This source is %s too long!", "just *way*", 35, LITERAL("\0") }));
+    EXPECT(test_single<const char*>({ LITERAL("Hello World!\0"), "Hello Friend!", POISON, 13, LITERAL("Hello Friend\0") }));
+    EXPECT(test_single<const char*>({ LITERAL("Hello World!\0"), "This source is %s too long!", "just *way*", 35, LITERAL("This source \0") }));
+    EXPECT(test_single<const char*>({ LITERAL("x"), "This source is %s too long!", "just *way*", 35, LITERAL("\0") }));
 }
 
 TEST_CASE(special_cases)
 {
-    EXPECT(test_single({ LITERAL(""), "Hello Friend!", POISON, 13, LITERAL("") }));
+    EXPECT(test_single<const char*>({ LITERAL(""), "Hello Friend!", POISON, 13, LITERAL("") }));
     EXPECT_EQ(snprintf(nullptr, 0, "Hello, friend!"), 14);
-    EXPECT(test_single({ LITERAL(""), "", POISON, 0, LITERAL("") }));
-    EXPECT(test_single({ LITERAL("x"), "", POISON, 0, LITERAL("\0") }));
-    EXPECT(test_single({ LITERAL("xx"), "", POISON, 0, LITERAL("\0x") }));
-    EXPECT(test_single({ LITERAL("xxx"), "", POISON, 0, LITERAL("\0xx") }));
-    EXPECT(test_single({ LITERAL(""), "whf", POISON, 3, LITERAL("") }));
-    EXPECT(test_single({ LITERAL("x"), "whf", POISON, 3, LITERAL("\0") }));
-    EXPECT(test_single({ LITERAL("xx"), "whf", POISON, 3, LITERAL("w\0") }));
+    EXPECT(test_single<const char*>({ LITERAL(""), "", POISON, 0, LITERAL("") }));
+    EXPECT(test_single<const char*>({ LITERAL("x"), "", POISON, 0, LITERAL("\0") }));
+    EXPECT(test_single<const char*>({ LITERAL("xx"), "", POISON, 0, LITERAL("\0x") }));
+    EXPECT(test_single<const char*>({ LITERAL("xxx"), "", POISON, 0, LITERAL("\0xx") }));
+    EXPECT(test_single<const char*>({ LITERAL(""), "whf", POISON, 3, LITERAL("") }));
+    EXPECT(test_single<const char*>({ LITERAL("x"), "whf", POISON, 3, LITERAL("\0") }));
+    EXPECT(test_single<const char*>({ LITERAL("xx"), "whf", POISON, 3, LITERAL("w\0") }));
+}
+
+TEST_CASE(octal_values)
+{
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%#10.5o|", 017, 12, LITERAL("|     00017|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%#10.5o|", 01000, 12, LITERAL("|     01000|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%#10.5o|", 010000, 12, LITERAL("|    010000|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%10.5o|", 017, 12, LITERAL("|     00017|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%-10.5o|", 017, 12, LITERAL("|00017     |\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%-010.5o|", 017, 12, LITERAL("|00017     |\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%010.5o|", 017, 12, LITERAL("|     00017|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%010o|", 017, 12, LITERAL("|0000000017|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%10o|", 017, 12, LITERAL("|        17|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxx\0"), "|%.5o|", 017, 7, LITERAL("|00017|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxx\0"), "|%.1o|", 017, 4, LITERAL("|17|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxx\0"), "|%.0o|", 017, 4, LITERAL("|17|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xx\0"), "|%.0o|", 00, 2, LITERAL("||\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxx\0"), "|%#.0o|", 00, 3, LITERAL("|0|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxx\0"), "|%#.0o|", 01, 4, LITERAL("|01|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxx\0"), "|%#.1o|", 00, 3, LITERAL("|0|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxx\0"), "|%#.1o|", 01, 4, LITERAL("|01|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxx\0"), "|%o|", 00, 3, LITERAL("|0|\0") }));
+}
+
+TEST_CASE(decimal_values)
+{
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%10.5d|", 17, 12, LITERAL("|     00017|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%+10.5d|", 17, 12, LITERAL("|    +00017|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%10.5d|", -17, 12, LITERAL("|    -00017|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%+10.5d|", -17, 12, LITERAL("|    -00017|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%-10.5d|", 17, 12, LITERAL("|00017     |\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%+-10.5d|", 17, 12, LITERAL("|+00017    |\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%+-10.5d|", -17, 12, LITERAL("|-00017    |\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%-10.5d|", -17, 12, LITERAL("|-00017    |\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%-010.5d|", 17, 12, LITERAL("|00017     |\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%010.5d|", 17, 12, LITERAL("|     00017|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%010d|", 17, 12, LITERAL("|0000000017|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%+010d|", 17, 12, LITERAL("|+000000017|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%010d|", -17, 12, LITERAL("|-000000017|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%010d|", 170000000, 12, LITERAL("|0170000000|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%+010d|", 170000000, 12, LITERAL("|+170000000|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%10d|", -170000000, 12, LITERAL("|-170000000|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%+10d|", -170000000, 12, LITERAL("|-170000000|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%010d|", 1700000000, 12, LITERAL("|1700000000|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxxx\0"), "|%+010d|", 1700000000, 13, LITERAL("|+1700000000|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxxx\0"), "|%10d|", -1700000000, 13, LITERAL("|-1700000000|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxxx\0"), "|%+10d|", -1700000000, 13, LITERAL("|-1700000000|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%10d|", 17, 12, LITERAL("|        17|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%+10d|", 17, 12, LITERAL("|       +17|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%10d|", -17, 12, LITERAL("|       -17|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxx\0"), "|%.5d|", 17, 7, LITERAL("|00017|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxx\0"), "|%.1d|", 17, 4, LITERAL("|17|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxx\0"), "|%.0d|", 17, 4, LITERAL("|17|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xx\0"), "|%.0d|", 0, 2, LITERAL("||\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxx\0"), "|%+.0d|", 0, 3, LITERAL("|+|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxx\0"), "|%#.1d|", 0, 3, LITERAL("|0|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxx\0"), "|%d|", 0, 3, LITERAL("|0|\0") }));
+}
+
+TEST_CASE(unsigned_decimal_values)
+{
+    EXPECT(test_single<unsigned int>({ LITERAL("xxxxxxxxxxxx\0"), "|%10.5u|", 17, 12, LITERAL("|     00017|\0") }));
+    EXPECT(test_single<unsigned int>({ LITERAL("xxxxxxxxxxxx\0"), "|%+10.5u|", 17, 12, LITERAL("|     00017|\0") }));
+    EXPECT(test_single<unsigned int>({ LITERAL("xxxxxxxxxxxx\0"), "|%-10.5u|", 17, 12, LITERAL("|00017     |\0") }));
+    EXPECT(test_single<unsigned int>({ LITERAL("xxxxxxxxxxxx\0"), "|%+-10.5u|", 17, 12, LITERAL("|00017     |\0") }));
+    EXPECT(test_single<unsigned int>({ LITERAL("xxxxxxxxxxxx\0"), "|%-010.5u|", 17, 12, LITERAL("|00017     |\0") }));
+    EXPECT(test_single<unsigned int>({ LITERAL("xxxxxxxxxxxx\0"), "|%010.5u|", 17, 12, LITERAL("|     00017|\0") }));
+    EXPECT(test_single<unsigned int>({ LITERAL("xxxxxxxxxxxx\0"), "|%010u|", 17, 12, LITERAL("|0000000017|\0") }));
+    EXPECT(test_single<unsigned int>({ LITERAL("xxxxxxxxxxxx\0"), "|%+010u|", 17, 12, LITERAL("|0000000017|\0") }));
+    EXPECT(test_single<unsigned int>({ LITERAL("xxxxxxxxxxxx\0"), "|%010u|", 170000000, 12, LITERAL("|0170000000|\0") }));
+    EXPECT(test_single<unsigned int>({ LITERAL("xxxxxxxxxxxx\0"), "|%+010u|", 170000000, 12, LITERAL("|0170000000|\0") }));
+    EXPECT(test_single<unsigned int>({ LITERAL("xxxxxxxxxxxx\0"), "|%010u|", 1700000000, 12, LITERAL("|1700000000|\0") }));
+    EXPECT(test_single<unsigned int>({ LITERAL("xxxxxxxxxxxx\0"), "|%+010u|", 1700000000, 12, LITERAL("|1700000000|\0") }));
+    EXPECT(test_single<unsigned int>({ LITERAL("xxxxxxxxxxxx\0"), "|%10u|", 17, 12, LITERAL("|        17|\0") }));
+    EXPECT(test_single<unsigned int>({ LITERAL("xxxxxxxxxxxx\0"), "|%+10u|", 17, 12, LITERAL("|        17|\0") }));
+    EXPECT(test_single<unsigned int>({ LITERAL("xxxxxxx\0"), "|%.5u|", 17, 7, LITERAL("|00017|\0") }));
+    EXPECT(test_single<unsigned int>({ LITERAL("xxxx\0"), "|%.1u|", 17, 4, LITERAL("|17|\0") }));
+    EXPECT(test_single<unsigned int>({ LITERAL("xxxx\0"), "|%.0u|", 17, 4, LITERAL("|17|\0") }));
+    EXPECT(test_single<unsigned int>({ LITERAL("xx\0"), "|%.0u|", 0, 2, LITERAL("||\0") }));
+    EXPECT(test_single<unsigned int>({ LITERAL("xx\0"), "|%+.0u|", 0, 2, LITERAL("||\0") }));
+    EXPECT(test_single<unsigned int>({ LITERAL("xxx\0"), "|%#.1u|", 0, 3, LITERAL("|0|\0") }));
+    EXPECT(test_single<unsigned int>({ LITERAL("xxx\0"), "|%u|", 0, 3, LITERAL("|0|\0") }));
+}
+
+TEST_CASE(hexadecimal_values)
+{
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%10.5X|", 0xab, 12, LITERAL("|     000AB|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%#10.5X|", 0xab, 12, LITERAL("|   0x000AB|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%10.5x|", 0xab, 12, LITERAL("|     000ab|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%#10.5x|", 0xab, 12, LITERAL("|   0x000ab|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%10.5x|", 0x1000, 12, LITERAL("|     01000|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%#10.5x|", 0x1000, 12, LITERAL("|   0x01000|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%10.5x|", 0x10000, 12, LITERAL("|     10000|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%#10.5x|", 0x10000, 12, LITERAL("|   0x10000|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%10.5x|", 0x17, 12, LITERAL("|     00017|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%-#10.5x|", 0x17, 12, LITERAL("|0x00017   |\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%-10.5x|", 0x17, 12, LITERAL("|00017     |\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%-010.5x|", 0x17, 12, LITERAL("|00017     |\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%010.5x|", 0x17, 12, LITERAL("|     00017|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%010x|", 0x17, 12, LITERAL("|0000000017|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%#010x|", 0x17, 12, LITERAL("|0x00000017|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%10x|", 0x17, 12, LITERAL("|        17|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxxxxx\0"), "|%#10x|", 0x17, 12, LITERAL("|      0x17|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxx\0"), "|%.5x|", 0x17, 7, LITERAL("|00017|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxxxxx\0"), "|%#.5x|", 0x17, 9, LITERAL("|0x00017|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxx\0"), "|%.1x|", 0x17, 4, LITERAL("|17|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxx\0"), "|%.0x|", 0x17, 4, LITERAL("|17|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xx\0"), "|%.0x|", 0x0, 2, LITERAL("||\0") }));
+    EXPECT(test_single<int>({ LITERAL("xx\0"), "|%#.0x|", 0x0, 2, LITERAL("||\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxx\0"), "|%4.0x|", 0x0, 6, LITERAL("|    |\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxx\0"), "|%04.0x|", 0x0, 6, LITERAL("|    |\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxx\0"), "|%#4.0x|", 0x0, 6, LITERAL("|    |\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxxx\0"), "|%#04.0x|", 0x0, 6, LITERAL("|    |\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxx\0"), "|%#.0x|", 0x1, 5, LITERAL("|0x1|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxx\0"), "|%#.1x|", 0x0, 3, LITERAL("|0|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxx\0"), "|%.1x|", 0x0, 3, LITERAL("|0|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxx\0"), "|%x|", 0x0, 3, LITERAL("|0|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxxxx\0"), "|%#.1x|", 0x1, 5, LITERAL("|0x1|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxx\0"), "|%x|", 0, 3, LITERAL("|0|\0") }));
+    EXPECT(test_single<int>({ LITERAL("xxx\0"), "|%#x|", 0, 3, LITERAL("|0|\0") }));
 }