diff --git a/libluna/include/luna/Check.h b/libluna/include/luna/Check.h
index 07c5279c..2cb1201b 100644
--- a/libluna/include/luna/Check.h
+++ b/libluna/include/luna/Check.h
@@ -1,6 +1,26 @@
+/**
+ * @file Check.h
+ * @author apio (cloudapio.eu)
+ * @brief Always-enabled assertions.
+ *
+ * @copyright Copyright (c) 2022-2023, the Luna authors.
+ *
+ */
+
 #pragma once
 #include <luna/SourceLocation.h>
 
+/**
+ * @brief Called when a libluna assertion fails. Some targets already have implementations of this function, but
+ * otherwise it must be implemented by the user.
+ *
+ * In the kernel, the implementation is in src/Log.cpp.
+ * For POSIX systems, libluna provides an implementation in src/ImplPOSIX.cpp.
+ *
+ * @param location The source location at which the assertion failure occurred.
+ * @param expr The expression or custom error message to display.
+ * @return bool Unused, since the function never returns.
+ */
 [[noreturn]] extern bool __check_failed(SourceLocation location, const char* expr);
 
 #ifndef STRINGIZE_VALUE_OF
@@ -8,32 +28,63 @@
 #define STRINGIZE_VALUE_OF(x) STRINGIZE(x)
 #endif
 
-// Like check(), but with a custom error message.
+/**
+ * @brief Verify an expression is true, or crash at runtime with a custom error message.
+ */
 #define expect(expr, message)                                                                                          \
     do {                                                                                                               \
         if (!(expr)) [[unlikely]] { __check_failed(SourceLocation::current(), message); }                              \
     } while (0)
 
+/**
+ * @brief Verify an expression is true, or crash at runtime with a custom error message, indicating a different source
+ * location (useful for reporting caller errors, see Result::release_value() for an example).
+ */
 #define expect_at(expr, location, message)                                                                             \
     do {                                                                                                               \
         if (!(expr)) [[unlikely]] { __check_failed(location, message); }                                               \
     } while (0)
 
-// Fail with an error message and location.
+/**
+ * @brief Crash at runtime with a custom error message.
+ */
 #define fail(message) __check_failed(SourceLocation::current(), message)
+
+/**
+ * @brief Crash at runtime with a custom error message, indicating a different source location (useful for
+ * reporting caller errors, see Result::release_value() for an example).
+ */
 #define fail_at(location, message) __check_failed(location, message)
 
-// Like assert(), but always enabled.
+/**
+ * @brief Verify an expression is true, or crash at runtime.
+ */
 #define check(expr)                                                                                                    \
     do {                                                                                                               \
         if (!(expr)) [[unlikely]] { __check_failed(SourceLocation::current(), #expr); }                                \
     } while (0)
 
+/**
+ * @brief Verify an expression is true, or crash at runtime, indicating a different source location (useful for
+ * reporting caller errors, see Result::release_value() for an example).
+ */
 #define check_at(expr, location)                                                                                       \
     do {                                                                                                               \
         if (!(expr)) [[unlikely]] { __check_failed(location, #expr); }                                                 \
     } while (0)
 
+/**
+ * @brief Mark a code section as unreachable, which will crash if reached.
+ *
+ * Often it may be more performant to use the compiler's __builtin_unreachable() for this purpose (when the code is
+ * clearly unreachable but the compiler cannot figure it out on its own, see the implementation of _exit() in libc), if
+ * there is just no possible way for execution flow to reach this code segment, but the compiler builtin results in
+ * undefined behavior if reached. Therefore, if a bug may cause this unreachable code to be reached, you may prefer to
+ * use this macro as it has well-defined behavior (crashes at runtime).
+ */
 #define unreachable() __check_failed(SourceLocation::current(), "Reached unreachable code")
 
+/**
+ * @brief Mark a code section as unimplemented, which will crash if reached.
+ */
 #define todo() __check_failed(SourceLocation::current(), "Reached a TODO!")