diff --git a/libc/CMakeLists.txt b/libc/CMakeLists.txt
index 82081493..8f12027c 100644
--- a/libc/CMakeLists.txt
+++ b/libc/CMakeLists.txt
@@ -47,6 +47,7 @@ add_library(libc ${LIBC_SOURCES})
 add_dependencies(libc headers crtx-install)
 
 target_compile_options(libc PRIVATE -g -Wstack-usage=512)
+target_compile_options(libc PUBLIC -Wall -Wextra -Werror -Wno-error=stack-usage=)
 
 add_custom_target(libc-install
 	COMMAND ${CMAKE_COMMAND} -E copy_if_different ${CMAKE_CURRENT_BINARY_DIR}/libc.a ${BANAN_LIB}/
diff --git a/libc/pwd.cpp b/libc/pwd.cpp
index 05a8c3be..4cf53fa1 100644
--- a/libc/pwd.cpp
+++ b/libc/pwd.cpp
@@ -104,7 +104,7 @@ struct passwd* getpwnam(const char* name)
 {
 	passwd* pwd;
 	setpwent();
-	while (pwd = getpwent())
+	while ((pwd = getpwent()))
 		if (strcmp(pwd->pw_name, name) == 0)
 			return pwd;
 	return nullptr;
@@ -114,7 +114,7 @@ struct passwd* getpwuid(uid_t uid)
 {
 	passwd* pwd;
 	setpwent();
-	while (pwd = getpwent())
+	while ((pwd = getpwent()))
 		if (pwd->pw_uid == uid)
 			return pwd;
 	return nullptr;
diff --git a/libc/stdio.cpp b/libc/stdio.cpp
index 54f22045..63b00d93 100644
--- a/libc/stdio.cpp
+++ b/libc/stdio.cpp
@@ -13,7 +13,7 @@ struct FILE
 	bool eof		{ false };
 	bool error		{ false };
 
-	unsigned char buffer[BUFSIZ];
+	unsigned char buffer[BUFSIZ] {};
 	uint32_t buffer_index { 0 };
 };
 
@@ -260,7 +260,7 @@ size_t fread(void* buffer, size_t size, size_t nitems, FILE* file)
 
 	while (nread < target)
 	{
-		size_t ret = syscall(SYS_READ, file->fd, (uint8_t*)buffer + nread, target - nread);
+		ssize_t ret = syscall(SYS_READ, file->fd, (uint8_t*)buffer + nread, target - nread);
 
 		if (ret < 0)
 			file->error = true;
diff --git a/userspace/Shell/main.cpp b/userspace/Shell/main.cpp
index c62a22d9..1433070d 100644
--- a/userspace/Shell/main.cpp
+++ b/userspace/Shell/main.cpp
@@ -600,7 +600,6 @@ int execute_piped_commands(BAN::Vector<BAN::Vector<BAN::String>>& commands)
 	int next_stdin = STDIN_FILENO;
 	for (size_t i = 0; i < commands.size(); i++)
 	{
-		bool first = (i == 0);
 		bool last  = (i == commands.size() - 1);
 
 		int pipefd[2] { -1, STDOUT_FILENO };
@@ -831,7 +830,7 @@ int prompt_length()
 void print_prompt()
 {
 	auto prompt = get_prompt();
-	fprintf(stdout, "%.*s", prompt.size(), prompt.data());
+	fprintf(stdout, "%.*s", (int)prompt.size(), prompt.data());
 	fflush(stdout);
 }
 
diff --git a/userspace/aoc2023/day10/main.cpp b/userspace/aoc2023/day10/main.cpp
index 0e3b58a7..175a0704 100644
--- a/userspace/aoc2023/day10/main.cpp
+++ b/userspace/aoc2023/day10/main.cpp
@@ -3,6 +3,7 @@
 #include <BAN/Vector.h>
 
 #include <ctype.h>
+#include <inttypes.h>
 #include <stdio.h>
 #include <stdint.h>
 
@@ -85,13 +86,13 @@ BAN::Array<Position, 2> find_grid_first_moves(const Grid& grid)
 			if (grid[y][x] == 'S')
 			{
 				size_t index = 0;
-				if (can_enter_tile_from(grid[y - 1][x], Direction::South))
+				if (index < 2 && can_enter_tile_from(grid[y - 1][x], Direction::South))
 					positions[index++] = { x, y - 1, Direction::South };
-				if (can_enter_tile_from(grid[y + 1][x], Direction::North))
+				if (index < 2 && can_enter_tile_from(grid[y + 1][x], Direction::North))
 					positions[index++] = { x, y + 1, Direction::North };
-				if (can_enter_tile_from(grid[y][x - 1], Direction::East))
+				if (index < 2 && can_enter_tile_from(grid[y][x - 1], Direction::East))
 					positions[index++] = { x - 1, y, Direction::East };
-				if (can_enter_tile_from(grid[y][x + 1], Direction::West))
+				if (index < 2 && can_enter_tile_from(grid[y][x + 1], Direction::West))
 					positions[index++] = { x + 1, y, Direction::West };
 				ASSERT(index == 2);
 				return positions;
@@ -268,11 +269,11 @@ int main(int argc, char** argv)
 		return 1;
 	}
 
-	printf("puzzle1: %lld\n", puzzle1(fp));
+	printf("puzzle1: %" PRId64 "\n", puzzle1(fp));
 
 	fseek(fp, 0, SEEK_SET);
 
-	printf("puzzle2: %lld\n", puzzle2(fp));
+	printf("puzzle2: %" PRId64 "\n", puzzle2(fp));
 
 	fclose(fp);
 }
diff --git a/userspace/aoc2023/day2/main.cpp b/userspace/aoc2023/day2/main.cpp
index 957dd157..6ea627d0 100644
--- a/userspace/aoc2023/day2/main.cpp
+++ b/userspace/aoc2023/day2/main.cpp
@@ -64,7 +64,7 @@ int puzzle2(FILE* fp)
 			continue;
 		ptr += 5;
 	
-		int id = parse_int_and_advance(ptr);
+		parse_int_and_advance(ptr);
 		ptr += 2;
 
 		int needed_red = 0;
diff --git a/userspace/aoc2023/day3/main.cpp b/userspace/aoc2023/day3/main.cpp
index 7e96bc52..2f65b471 100644
--- a/userspace/aoc2023/day3/main.cpp
+++ b/userspace/aoc2023/day3/main.cpp
@@ -21,9 +21,9 @@ int puzzle1(FILE* fp)
 
 	int result = 0;
 
-	for (ssize_t y = 0; y < lines.size(); y++)
+	for (size_t y = 0; y < lines.size(); y++)
 	{
-		for (ssize_t x = 0; x < lines[y].size(); x++)
+		for (size_t x = 0; x < lines[y].size(); x++)
 		{			
 			if (!isdigit(lines[y][x]))
 				continue;
@@ -32,14 +32,14 @@ int puzzle1(FILE* fp)
 
 			for (ssize_t y_off = -1; y_off <= 1; y_off++)
 			{
-				if (y + y_off < 0)
+				if ((ssize_t)y < y_off)
 					continue;
 				if (y + y_off >= lines.size())
 					break;
 
 				for (ssize_t x_off = -1;; x_off++)
 				{
-					if (x + x_off < 0)
+					if ((ssize_t)x < x_off)
 						continue;
 					if (x + x_off >= lines[y + y_off].size())
 						break;
@@ -94,9 +94,9 @@ int puzzle2(FILE* fp)
 	// Map numbers next to '*' to asterisk's coordinates.
 	HashMap<uint32_t, Vector<int>> gears;
 
-	for (ssize_t y = 0; y < lines.size(); y++)
+	for (size_t y = 0; y < lines.size(); y++)
 	{
-		for (ssize_t x = 0; x < lines[y].size(); x++)
+		for (size_t x = 0; x < lines[y].size(); x++)
 		{
 			if (!isdigit(lines[y][x]))
 				continue;
@@ -111,14 +111,14 @@ int puzzle2(FILE* fp)
 
 			for (ssize_t y_off = -1; y_off <= 1; y_off++)
 			{
-				if (y + y_off < 0)
+				if ((ssize_t)y < y_off)
 					continue;
 				if (y + y_off >= lines.size())
 					break;
 
 				for (ssize_t x_off = -1;; x_off++)
 				{
-					if (x + x_off < 0)
+					if ((ssize_t)x < x_off)
 						continue;
 					if (x + x_off >= lines[y + y_off].size())
 						break;
diff --git a/userspace/aoc2023/day5/main.cpp b/userspace/aoc2023/day5/main.cpp
index f819fb9e..8e33608c 100644
--- a/userspace/aoc2023/day5/main.cpp
+++ b/userspace/aoc2023/day5/main.cpp
@@ -1,6 +1,7 @@
 #include <BAN/HashMap.h>
 #include <BAN/Vector.h>
 
+#include <inttypes.h>
 #include <stdio.h>
 
 using i64 = int64_t;
@@ -31,7 +32,7 @@ i64 puzzle1(FILE* fp)
 		line = line.substring(0, line.size() - 1);
 
 		auto seeds_str = MUST(line.split(' '));
-		for (i64 i = 1; i < seeds_str.size(); i++)
+		for (size_t i = 1; i < seeds_str.size(); i++)
 			MUST(current.emplace_back(parse_i64(seeds_str[i]), 0));
 	}
 
@@ -92,7 +93,7 @@ i64 puzzle2(FILE* fp)
 		BAN::StringView line(buffer);
 		line = line.substring(0, line.size() - 1);
 		auto seeds_str = MUST(line.split(' '));
-		for (i64 i = 1; i < seeds_str.size(); i += 2)
+		for (size_t i = 1; i < seeds_str.size(); i += 2)
 			MUST(current.emplace_back(parse_i64(seeds_str[i]), parse_i64(seeds_str[i + 1]), 0));
 	}
 
@@ -179,11 +180,11 @@ int main(int argc, char** argv)
 		return 1;
 	}
 
-	printf("puzzle1: %lld\n", puzzle1(fp));
+	printf("puzzle1: %" PRId64 "\n", puzzle1(fp));
 
 	fseek(fp, 0, SEEK_SET);
 
-	printf("puzzle2: %lld\n", puzzle2(fp));
+	printf("puzzle2: %" PRId64 "\n", puzzle2(fp));
 
 	fclose(fp);
 }
diff --git a/userspace/aoc2023/day6/main.cpp b/userspace/aoc2023/day6/main.cpp
index b857fc51..a56d62c3 100644
--- a/userspace/aoc2023/day6/main.cpp
+++ b/userspace/aoc2023/day6/main.cpp
@@ -1,6 +1,7 @@
 #include <BAN/Vector.h>
 
 #include <ctype.h>
+#include <inttypes.h>
 #include <stdio.h>
 #include <stdint.h>
 
@@ -112,11 +113,11 @@ int main(int argc, char** argv)
 		return 1;
 	}
 
-	printf("puzzle1: %lld\n", puzzle1(fp));
+	printf("puzzle1: %" PRId64 "\n", puzzle1(fp));
 
 	fseek(fp, 0, SEEK_SET);
 
-	printf("puzzle2: %lld\n", puzzle2(fp));
+	printf("puzzle1: %" PRId64 "\n", puzzle2(fp));
 
 	fclose(fp);
 }
diff --git a/userspace/aoc2023/day7/main.cpp b/userspace/aoc2023/day7/main.cpp
index b1dbdbb2..bcfebdc0 100644
--- a/userspace/aoc2023/day7/main.cpp
+++ b/userspace/aoc2023/day7/main.cpp
@@ -3,6 +3,7 @@
 #include <BAN/String.h>
 
 #include <ctype.h>
+#include <inttypes.h>
 #include <stdio.h>
 #include <stdint.h>
 
@@ -142,11 +143,11 @@ int main(int argc, char** argv)
 		return 1;
 	}
 
-	printf("puzzle1: %lld\n", puzzle(fp, false));
+	printf("puzzle1: %" PRId64 "\n", puzzle(fp, false));
 
 	fseek(fp, 0, SEEK_SET);
 
-	printf("puzzle2: %lld\n", puzzle(fp, true));
+	printf("puzzle2: %" PRId64 "\n", puzzle(fp, true));
 
 	fclose(fp);
 }
diff --git a/userspace/aoc2023/day8/main.cpp b/userspace/aoc2023/day8/main.cpp
index 4ec0410d..a4be9173 100644
--- a/userspace/aoc2023/day8/main.cpp
+++ b/userspace/aoc2023/day8/main.cpp
@@ -2,6 +2,7 @@
 #include <BAN/String.h>
 
 #include <ctype.h>
+#include <inttypes.h>
 #include <stdio.h>
 #include <stdint.h>
 
@@ -121,11 +122,11 @@ int main(int argc, char** argv)
 		return 1;
 	}
 
-	printf("puzzle1: %lld\n", puzzle1(fp));
+	printf("puzzle1: %" PRId64 "\n", puzzle1(fp));
 
 	fseek(fp, 0, SEEK_SET);
 
-	printf("puzzle2: %lld\n", puzzle2(fp));
+	printf("puzzle2: %" PRId64 "\n", puzzle2(fp));
 
 	fclose(fp);
 }
diff --git a/userspace/aoc2023/day9/main.cpp b/userspace/aoc2023/day9/main.cpp
index a23bc44a..d5637203 100644
--- a/userspace/aoc2023/day9/main.cpp
+++ b/userspace/aoc2023/day9/main.cpp
@@ -2,6 +2,7 @@
 #include <BAN/Vector.h>
 
 #include <ctype.h>
+#include <inttypes.h>
 #include <stdio.h>
 #include <stdint.h>
 
@@ -114,11 +115,11 @@ int main(int argc, char** argv)
 		return 1;
 	}
 
-	printf("puzzle1: %lld\n", puzzle1(fp));
+	printf("puzzle1: %" PRId64 "\n", puzzle1(fp));
 
 	fseek(fp, 0, SEEK_SET);
 
-	printf("puzzle2: %lld\n", puzzle2(fp));
+	printf("puzzle2: %" PRId64 "\n", puzzle2(fp));
 
 	fclose(fp);
 }
diff --git a/userspace/cat/main.cpp b/userspace/cat/main.cpp
index 28b43095..cd367580 100644
--- a/userspace/cat/main.cpp
+++ b/userspace/cat/main.cpp
@@ -4,7 +4,6 @@
 bool cat_file(int fd)
 {
 	char buffer[1024];
-	size_t n_read;
 	while (ssize_t n_read = read(fd, buffer, sizeof(buffer)))
 	{
 		if (n_read == -1)
diff --git a/userspace/cp/main.cpp b/userspace/cp/main.cpp
index 58d8a5c0..e3d3acdc 100644
--- a/userspace/cp/main.cpp
+++ b/userspace/cp/main.cpp
@@ -59,7 +59,7 @@ bool copy_file(const BAN::String& source, BAN::String destination)
 			break;
 		}
 
-		size_t written = 0;
+		ssize_t written = 0;
 		while (written < nread)
 		{
 			ssize_t nwrite = write(dest_fd, buffer, nread - written);
diff --git a/userspace/dd/main.cpp b/userspace/dd/main.cpp
index 0b574b21..0d105676 100644
--- a/userspace/dd/main.cpp
+++ b/userspace/dd/main.cpp
@@ -10,9 +10,7 @@
 int parse_int(const char* val)
 {
 	int result = 0;
-
-	const char* ptr = val;
-	while (*ptr)
+	for (const char* ptr = val; *ptr; ptr++)
 	{
 		if (!isdigit(*ptr))
 		{
@@ -20,9 +18,7 @@ int parse_int(const char* val)
 			exit(1);
 		}
 		result = (result * 10) + (*ptr - '0');
-		*ptr++;
 	}
-
 	return result;
 }
 
diff --git a/userspace/image/Netbpm.cpp b/userspace/image/Netbpm.cpp
index 5f424882..93cd69bf 100644
--- a/userspace/image/Netbpm.cpp
+++ b/userspace/image/Netbpm.cpp
@@ -3,6 +3,7 @@
 #include <BAN/Optional.h>
 
 #include <ctype.h>
+#include <inttypes.h>
 #include <stdio.h>
 
 BAN::Optional<uint64_t> parse_u64(const uint8_t*& data, size_t data_size)
@@ -86,7 +87,7 @@ BAN::ErrorOr<BAN::UniqPtr<Image>> load_netbpm(const void* mmap_addr, size_t size
 		return BAN::Error::from_errno(EINVAL);
 	}
 
-	printf("Netbpm image %llux%llu\n", *width, *height);
+	printf("Netbpm image %" PRIuPTR "x%" PRIuPTR "\n", *width, *height);
 
 	BAN::Vector<Image::Color> bitmap;
 	TRY(bitmap.resize(*width * *height));
diff --git a/userspace/ls/main.cpp b/userspace/ls/main.cpp
index 9a3c42ec..f060a159 100644
--- a/userspace/ls/main.cpp
+++ b/userspace/ls/main.cpp
@@ -138,7 +138,7 @@ int list_directory(const BAN::String& path, config_t config)
 		}
 
 		struct dirent* dirent;
-		while (dirent = readdir(dirp))
+		while ((dirent = readdir(dirp)))
 		{
 			if (!config.all && dirent->d_name[0] == '.')
 				continue;
@@ -216,15 +216,15 @@ int list_directory(const BAN::String& path, config_t config)
 
 	for (const auto& full_entry : full_entries)
 		printf("%*s %*s %*s %*s %*s %*s %*s %*s %s\n",
-			max_entry.access.size(),		full_entry.access.data(),
-			max_entry.hard_links.size(),	full_entry.hard_links.data(),
-			max_entry.owner_name.size(),	full_entry.owner_name.data(),
-			max_entry.owner_group.size(),	full_entry.owner_group.data(),
-			max_entry.size.size(),			full_entry.size.data(),
-			max_entry.month.size(),			full_entry.month.data(),
-			max_entry.day.size(),			full_entry.day.data(),
-			max_entry.time.size(),			full_entry.time.data(),
-			full_entry.full_name.data()
+			(int)max_entry.access.size(),		full_entry.access.data(),
+			(int)max_entry.hard_links.size(),	full_entry.hard_links.data(),
+			(int)max_entry.owner_name.size(),	full_entry.owner_name.data(),
+			(int)max_entry.owner_group.size(),	full_entry.owner_group.data(),
+			(int)max_entry.size.size(),			full_entry.size.data(),
+			(int)max_entry.month.size(),		full_entry.month.data(),
+			(int)max_entry.day.size(),			full_entry.day.data(),
+			(int)max_entry.time.size(),			full_entry.time.data(),
+												full_entry.full_name.data()
 		);
 
 	return ret;
diff --git a/userspace/poweroff/main.cpp b/userspace/poweroff/main.cpp
index 797281bf..197cbd02 100644
--- a/userspace/poweroff/main.cpp
+++ b/userspace/poweroff/main.cpp
@@ -6,7 +6,7 @@
 void usage(int ret, char* arg0)
 {
 	FILE* fout = (ret == 0) ? stdout : stderr;
-	fprintf(fout, "usage: %s [OPTIONS]...\n");
+	fprintf(fout, "usage: %s [OPTIONS]...\n", arg0);
 	fprintf(fout, "  -s, --shutdown  Shutdown the system (default)\n");
 	fprintf(fout, "  -r, --reboot    Reboot the system\n");
 	fprintf(fout, "  -h, --help      Show this message\n");
diff --git a/userspace/rm/main.cpp b/userspace/rm/main.cpp
index 664fccc1..d42e8bcc 100644
--- a/userspace/rm/main.cpp
+++ b/userspace/rm/main.cpp
@@ -54,13 +54,13 @@ bool delete_recursive(const char* path)
 		return false;
 	}
 
-	return true;
+	return ret;
 }
 
 void usage(const char* argv0, int ret)
 {
 	FILE* out = (ret == 0) ? stdout : stderr;
-	fprintf(out, "usage: %s [OPTIONS]... FILE...\n");
+	fprintf(out, "usage: %s [OPTIONS]... FILE...\n", argv0);
 	fprintf(out, "  remove each FILE\n");
 	fprintf(out, "OPTIONS:\n");
 	fprintf(out, "  -r           remove directories and their contents recursively\n");
diff --git a/userspace/snake/main.cpp b/userspace/snake/main.cpp
index bb532be0..b289a731 100644
--- a/userspace/snake/main.cpp
+++ b/userspace/snake/main.cpp
@@ -27,7 +27,7 @@ bool				g_running		= true;
 Point				g_grid_size		= { 21, 21 };
 Direction			g_direction		= Direction::Up;
 Point				g_head			= { 10, 10 };
-int					g_tail_target	= 3;
+size_t				g_tail_target	= 3;
 int					g_score			= 0;
 BAN::Vector<Point>	g_tail;
 Point				g_apple;
@@ -133,6 +133,8 @@ void update()
 				if (g_direction != Direction::Left)
 					new_direction = Direction::Right;
 				break;
+			default:
+				break;
 		}
 	}
 
@@ -154,6 +156,8 @@ void update()
 		case Direction::Right:
 			g_head.x++;
 			break;
+		default:
+			ASSERT_NOT_REACHED();
 	}
 
 	if (g_head.x < 0 || g_head.y < 0 || g_head.x >= g_grid_size.x || g_head.y >= g_grid_size.y)
diff --git a/userspace/stat/main.cpp b/userspace/stat/main.cpp
index af230e68..a24265e7 100644
--- a/userspace/stat/main.cpp
+++ b/userspace/stat/main.cpp
@@ -7,7 +7,7 @@
 void print_timestamp(timespec ts)
 {
 	auto time = BAN::from_unix_time(ts.tv_sec);
-	printf("%04d-%02d-%02d %02d:%02d:%02d.%09d",
+	printf("%04d-%02d-%02d %02d:%02d:%02d.%09ld",
 		time.year, time.month, time.day,
 		time.hour, time.minute, time.second,
 		ts.tv_nsec
diff --git a/userspace/u8sum/main.cpp b/userspace/u8sum/main.cpp
index 7cc2b8ce..db15c8f2 100644
--- a/userspace/u8sum/main.cpp
+++ b/userspace/u8sum/main.cpp
@@ -16,7 +16,7 @@ int main(int argc, char** argv)
 
 		uint8_t buffer[1024];
 		while (size_t ret = fread(buffer, 1, sizeof(buffer), fp))
-			for (int j = 0; j < ret; j++)
+			for (size_t j = 0; j < ret; j++)
 				sum += buffer[j];
 
 		if (ferror(fp))