diff --git a/kernel/kernel/FS/FAT/Inode.cpp b/kernel/kernel/FS/FAT/Inode.cpp
index 642ec785..49d12f2a 100644
--- a/kernel/kernel/FS/FAT/Inode.cpp
+++ b/kernel/kernel/FS/FAT/Inode.cpp
@@ -30,19 +30,19 @@ namespace Kernel
 
 	timespec FATInode::atime() const
 	{
-		uint64_t epoch = fat_date_to_epoch(m_entry.last_access_date, {});
+		const time_t epoch = fat_date_to_epoch(m_entry.last_access_date, {});
 		return timespec { .tv_sec = epoch, .tv_nsec = 0 };
 	}
 
 	timespec FATInode::mtime() const
 	{
-		uint64_t epoch = fat_date_to_epoch(m_entry.write_date, m_entry.write_time);
+		const time_t epoch = fat_date_to_epoch(m_entry.write_date, m_entry.write_time);
 		return timespec { .tv_sec = epoch, .tv_nsec = 0 };
 	}
 
 	timespec FATInode::ctime() const
 	{
-		uint64_t epoch = fat_date_to_epoch(m_entry.creation_date, m_entry.creation_time);
+		const time_t epoch = fat_date_to_epoch(m_entry.creation_date, m_entry.creation_time);
 		return timespec { .tv_sec = epoch, .tv_nsec = 0 };
 	}
 
diff --git a/kernel/kernel/Timer/HPET.cpp b/kernel/kernel/Timer/HPET.cpp
index e7cdf2a2..e4b9cd1c 100644
--- a/kernel/kernel/Timer/HPET.cpp
+++ b/kernel/kernel/Timer/HPET.cpp
@@ -299,7 +299,7 @@ namespace Kernel
 		long ns_this_second = ticks_this_second * regs.counter_clk_period / FS_PER_NS;
 
 		return timespec {
-			.tv_sec = seconds,
+			.tv_sec = static_cast<time_t>(seconds),
 			.tv_nsec = ns_this_second
 		};
 	}
diff --git a/userspace/libraries/LibC/include/sys/types.h b/userspace/libraries/LibC/include/sys/types.h
index 896ce206..a6bf10b0 100644
--- a/userspace/libraries/LibC/include/sys/types.h
+++ b/userspace/libraries/LibC/include/sys/types.h
@@ -146,7 +146,7 @@ __BEGIN_DECLS
 
 #if !defined(__time_t_defined) && (defined(__need_all_types) || defined(__need_time_t))
 	#define __time_t_defined 1
-	typedef unsigned long long time_t;
+	typedef long long time_t;
 #endif
 #undef __need_time_t
 
diff --git a/userspace/libraries/LibC/time.cpp b/userspace/libraries/LibC/time.cpp
index 9817f776..a7f13463 100644
--- a/userspace/libraries/LibC/time.cpp
+++ b/userspace/libraries/LibC/time.cpp
@@ -1,3 +1,4 @@
+#include <BAN/Assert.h>
 #include <BAN/Debug.h>
 #include <BAN/Math.h>
 
@@ -167,15 +168,18 @@ time_t mktime(struct tm* tm)
 
 struct tm* gmtime_r(const time_t* timer, struct tm* __restrict result)
 {
+	// FIXME: allow negative times :)
+	ASSERT(*timer >= 0);
+
 	constexpr uint64_t month_days[] { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 };
 
-	time_t time = *timer;
+	unsigned long long time = *timer;
 
 	result->tm_sec  = time % 60; time /= 60;
 	result->tm_min  = time % 60; time /= 60;
 	result->tm_hour = time % 24; time /= 24;
 
-	time_t total_days = time;
+	unsigned long long total_days = time;
 	result->tm_wday = (total_days + 4) % 7;
 	result->tm_year = 1970;
 	while (total_days >= 365U + is_leap_year(result->tm_year))