diff --git a/AK/Assertions.h b/AK/Assertions.h
index 0898b79a17daf1..bd2404cd68406e 100644
--- a/AK/Assertions.h
+++ b/AK/Assertions.h
@@ -3,7 +3,11 @@
 #ifdef KERNEL
 #include <Kernel/Assertions.h>
 #else
-#include <LibC/assert.h>
+#include <assert.h>
+#ifndef __serenity__
+#define ASSERT assert
+#define ASSERT_NOT_REACHED assert(false)
+#endif
 #endif
 
 namespace AK {
diff --git a/AK/StdLibExtras.h b/AK/StdLibExtras.h
index e953d16d6eb712..04c9ce72d0d072 100644
--- a/AK/StdLibExtras.h
+++ b/AK/StdLibExtras.h
@@ -3,8 +3,8 @@
 #ifdef KERNEL
 #include <Kernel/StdLib.h>
 #else
-#include <LibC/stdlib.h>
-#include <LibC/string.h>
+#include <stdlib.h>
+#include <string.h>
 #endif
 
 #define UNUSED_PARAM(x) (void)x
diff --git a/AK/Types.h b/AK/Types.h
index 050d4930cc88a1..fb8501d21dd438 100644
--- a/AK/Types.h
+++ b/AK/Types.h
@@ -1,6 +1,6 @@
 #pragma once
 
-#if defined(SERENITY)
+#ifdef __serenity__
 typedef unsigned char byte;
 typedef unsigned short word;
 typedef unsigned int dword;
diff --git a/AK/kmalloc.cpp b/AK/kmalloc.cpp
index f51bfd29102173..13ad812270fdb2 100644
--- a/AK/kmalloc.cpp
+++ b/AK/kmalloc.cpp
@@ -1,34 +1,11 @@
 #include "kmalloc.h"
 
-#ifndef SERENITY
+#ifndef __serenity__
 #include <cstdlib>
 #endif
 
 extern "C" {
 
-void* kcalloc(size_t nmemb, size_t size)
-{
-    return calloc(nmemb, size);
-}
-
-void* kmalloc(size_t size)
-{
-    return malloc(size);
-}
-
-void kfree(void* ptr)
-{
-    free(ptr);
-}
-
-void* krealloc(void* ptr, size_t size)
-{
-    return realloc(ptr, size);
-}
 
-void* kmalloc_eternal(size_t size)
-{
-    return kmalloc(size);
-}
 
 }
diff --git a/AK/kmalloc.h b/AK/kmalloc.h
index 99a3cd67bd7e7d..c31352ec010b02 100644
--- a/AK/kmalloc.h
+++ b/AK/kmalloc.h
@@ -1,6 +1,6 @@
 #pragma once
 
-#if defined(SERENITY) && defined(KERNEL)
+#ifdef KERNEL
 #define AK_MAKE_ETERNAL \
 public: \
     void* operator new(size_t size) { return kmalloc_eternal(size); } \
@@ -12,17 +12,14 @@ public: \
 #ifdef KERNEL
 #include <Kernel/kmalloc.h>
 #else
-#include <LibC/stdlib.h>
-
-extern "C" {
+#include <stdlib.h>
 
-[[gnu::malloc, gnu::returns_nonnull]] void* kmalloc(size_t size);
-[[gnu::malloc, gnu::returns_nonnull]] void* kmalloc_eternal(size_t);
-[[gnu::returns_nonnull]] void* krealloc(void* ptr, size_t size);
-void kfree(void* ptr);
-
-}
+#define kcalloc calloc
+#define kmalloc malloc
+#define kfree free
+#define krealloc realloc
 
+#ifdef __serenity__
 inline void* operator new(size_t size)
 {
     return kmalloc(size);
@@ -47,5 +44,6 @@ inline void* operator new(size_t, void* ptr)
 {
     return ptr;
 }
+#endif
 
 #endif
diff --git a/Applications/About/Makefile b/Applications/About/Makefile
index 19612e3f2098ab..a3170934defe21 100644
--- a/Applications/About/Makefile
+++ b/Applications/About/Makefile
@@ -9,7 +9,7 @@ FLAVOR_FLAGS = -fno-exceptions -fno-rtti
 OPTIMIZATION_FLAGS = -Os
 INCLUDE_FLAGS = -I../.. -I. -I../../LibC
 
-DEFINES = -DSERENITY -DSANITIZE_PTRS -DUSERLAND
+DEFINES = -DSANITIZE_PTRS -DUSERLAND
 
 CXXFLAGS = -MMD -MP $(WARNING_FLAGS) $(OPTIMIZATION_FLAGS) $(FLAVOR_FLAGS) $(STANDARD_FLAGS) $(INCLUDE_FLAGS) $(DEFINES)
 CXX = i686-pc-serenity-g++
diff --git a/Applications/Downloader/Makefile b/Applications/Downloader/Makefile
index 9d417a883ab52a..0a16ef941900c5 100644
--- a/Applications/Downloader/Makefile
+++ b/Applications/Downloader/Makefile
@@ -9,7 +9,7 @@ FLAVOR_FLAGS = -fno-exceptions -fno-rtti
 OPTIMIZATION_FLAGS = -Os
 INCLUDE_FLAGS = -I../../Servers -I../.. -I. -I../../LibC
 
-DEFINES = -DSERENITY -DSANITIZE_PTRS -DUSERLAND
+DEFINES = -DSANITIZE_PTRS -DUSERLAND
 
 CXXFLAGS = -MMD -MP $(WARNING_FLAGS) $(OPTIMIZATION_FLAGS) $(FLAVOR_FLAGS) $(STANDARD_FLAGS) $(INCLUDE_FLAGS) $(DEFINES)
 CXX = i686-pc-serenity-g++
diff --git a/Applications/FileManager/Makefile b/Applications/FileManager/Makefile
index 5b94becf18dc31..51209560e4b89c 100644
--- a/Applications/FileManager/Makefile
+++ b/Applications/FileManager/Makefile
@@ -11,7 +11,7 @@ FLAVOR_FLAGS = -fno-exceptions -fno-rtti
 OPTIMIZATION_FLAGS = -Os
 INCLUDE_FLAGS = -I../.. -I../../Servers -I. -I../../LibC
 
-DEFINES = -DSERENITY -DSANITIZE_PTRS -DUSERLAND
+DEFINES = -DSANITIZE_PTRS -DUSERLAND
 
 CXXFLAGS = -MMD -MP $(WARNING_FLAGS) $(OPTIMIZATION_FLAGS) $(FLAVOR_FLAGS) $(STANDARD_FLAGS) $(INCLUDE_FLAGS) $(DEFINES)
 CXX = i686-pc-serenity-g++
diff --git a/Applications/FontEditor/Makefile b/Applications/FontEditor/Makefile
index b8d335bc1e9889..c4190895eed9db 100644
--- a/Applications/FontEditor/Makefile
+++ b/Applications/FontEditor/Makefile
@@ -12,7 +12,7 @@ FLAVOR_FLAGS = -fno-exceptions -fno-rtti
 OPTIMIZATION_FLAGS = -Os
 INCLUDE_FLAGS = -I../.. -I. -I../../LibC
 
-DEFINES = -DSERENITY -DSANITIZE_PTRS -DUSERLAND
+DEFINES = -DSANITIZE_PTRS -DUSERLAND
 
 CXXFLAGS = -MMD -MP $(WARNING_FLAGS) $(OPTIMIZATION_FLAGS) $(FLAVOR_FLAGS) $(STANDARD_FLAGS) $(INCLUDE_FLAGS) $(DEFINES)
 CXX = i686-pc-serenity-g++
diff --git a/Applications/IRCClient/Makefile b/Applications/IRCClient/Makefile
index bb2ebaf1b094de..c61164768cfb47 100644
--- a/Applications/IRCClient/Makefile
+++ b/Applications/IRCClient/Makefile
@@ -18,7 +18,7 @@ FLAVOR_FLAGS = -fno-exceptions -fno-rtti
 OPTIMIZATION_FLAGS = -Os
 INCLUDE_FLAGS = -I../../Servers -I../.. -I. -I../../LibC
 
-DEFINES = -DSERENITY -DSANITIZE_PTRS -DUSERLAND
+DEFINES = -DSANITIZE_PTRS -DUSERLAND
 
 CXXFLAGS = -MMD -MP $(WARNING_FLAGS) $(OPTIMIZATION_FLAGS) $(FLAVOR_FLAGS) $(STANDARD_FLAGS) $(INCLUDE_FLAGS) $(DEFINES)
 CXX = i686-pc-serenity-g++
diff --git a/Applications/Launcher/Makefile b/Applications/Launcher/Makefile
index 30651fe518fdbb..7062a8f26622f7 100644
--- a/Applications/Launcher/Makefile
+++ b/Applications/Launcher/Makefile
@@ -9,7 +9,7 @@ FLAVOR_FLAGS = -fno-exceptions -fno-rtti
 OPTIMIZATION_FLAGS = -Os
 INCLUDE_FLAGS = -I../.. -I. -I../../LibC
 
-DEFINES = -DSERENITY -DSANITIZE_PTRS -DUSERLAND
+DEFINES = -DSANITIZE_PTRS -DUSERLAND
 
 CXXFLAGS = -MMD -MP $(WARNING_FLAGS) $(OPTIMIZATION_FLAGS) $(FLAVOR_FLAGS) $(STANDARD_FLAGS) $(INCLUDE_FLAGS) $(DEFINES)
 CXX = i686-pc-serenity-g++
diff --git a/Applications/ProcessManager/Makefile b/Applications/ProcessManager/Makefile
index 489897e5599fb0..6b6f007f5f1e17 100644
--- a/Applications/ProcessManager/Makefile
+++ b/Applications/ProcessManager/Makefile
@@ -12,7 +12,7 @@ FLAVOR_FLAGS = -fno-exceptions -fno-rtti
 OPTIMIZATION_FLAGS = -Os
 INCLUDE_FLAGS = -I../.. -I. -I../../LibC
 
-DEFINES = -DSERENITY -DSANITIZE_PTRS -DUSERLAND
+DEFINES = -DSANITIZE_PTRS -DUSERLAND
 
 CXXFLAGS = -MMD -MP $(WARNING_FLAGS) $(OPTIMIZATION_FLAGS) $(FLAVOR_FLAGS) $(STANDARD_FLAGS) $(INCLUDE_FLAGS) $(DEFINES)
 CXX = i686-pc-serenity-g++
diff --git a/Applications/Taskbar/Makefile b/Applications/Taskbar/Makefile
index 50277448bf7fa8..0c412c30397483 100644
--- a/Applications/Taskbar/Makefile
+++ b/Applications/Taskbar/Makefile
@@ -11,7 +11,7 @@ FLAVOR_FLAGS = -fno-exceptions -fno-rtti
 OPTIMIZATION_FLAGS = -Os
 INCLUDE_FLAGS = -I../.. -I../../Servers -I. -I../../LibC
 
-DEFINES = -DSERENITY -DSANITIZE_PTRS -DUSERLAND
+DEFINES = -DSANITIZE_PTRS -DUSERLAND
 
 CXXFLAGS = -MMD -MP $(WARNING_FLAGS) $(OPTIMIZATION_FLAGS) $(FLAVOR_FLAGS) $(STANDARD_FLAGS) $(INCLUDE_FLAGS) $(DEFINES)
 CXX = i686-pc-serenity-g++
diff --git a/Applications/Terminal/Makefile b/Applications/Terminal/Makefile
index f5d0a2ee479821..fddf7f11bbb384 100644
--- a/Applications/Terminal/Makefile
+++ b/Applications/Terminal/Makefile
@@ -10,7 +10,7 @@ FLAVOR_FLAGS = -fno-exceptions -fno-rtti
 OPTIMIZATION_FLAGS = -Os
 INCLUDE_FLAGS = -I../.. -I. -I../../LibC
 
-DEFINES = -DSERENITY -DSANITIZE_PTRS -DUSERLAND
+DEFINES = -DSANITIZE_PTRS -DUSERLAND
 
 CXXFLAGS = -MMD -MP $(WARNING_FLAGS) $(OPTIMIZATION_FLAGS) $(FLAVOR_FLAGS) $(STANDARD_FLAGS) $(INCLUDE_FLAGS) $(DEFINES)
 CXX = i686-pc-serenity-g++
diff --git a/Applications/TextEditor/Makefile b/Applications/TextEditor/Makefile
index 2e9f5fa92bb079..9d608c49baf7b1 100644
--- a/Applications/TextEditor/Makefile
+++ b/Applications/TextEditor/Makefile
@@ -9,7 +9,7 @@ FLAVOR_FLAGS = -fno-exceptions -fno-rtti
 OPTIMIZATION_FLAGS = -Os
 INCLUDE_FLAGS = -I../.. -I. -I../../LibC
 
-DEFINES = -DSERENITY -DSANITIZE_PTRS -DUSERLAND
+DEFINES = -DSANITIZE_PTRS -DUSERLAND
 
 CXXFLAGS = -MMD -MP $(WARNING_FLAGS) $(OPTIMIZATION_FLAGS) $(FLAVOR_FLAGS) $(STANDARD_FLAGS) $(INCLUDE_FLAGS) $(DEFINES)
 CXX = i686-pc-serenity-g++
diff --git a/Applications/VisualBuilder/Makefile b/Applications/VisualBuilder/Makefile
index c2bb96cce15713..5188ef20838cea 100644
--- a/Applications/VisualBuilder/Makefile
+++ b/Applications/VisualBuilder/Makefile
@@ -15,7 +15,7 @@ FLAVOR_FLAGS = -fno-exceptions -fno-rtti
 OPTIMIZATION_FLAGS = -Os
 INCLUDE_FLAGS = -I../.. -I. -I../../LibC
 
-DEFINES = -DSERENITY -DSANITIZE_PTRS -DUSERLAND
+DEFINES = -DSANITIZE_PTRS -DUSERLAND
 
 CXXFLAGS = -MMD -MP $(WARNING_FLAGS) $(OPTIMIZATION_FLAGS) $(FLAVOR_FLAGS) $(STANDARD_FLAGS) $(INCLUDE_FLAGS) $(DEFINES)
 CXX = i686-pc-serenity-g++
diff --git a/Games/Minesweeper/Makefile b/Games/Minesweeper/Makefile
index c074a823acf352..a289634ddd8c23 100644
--- a/Games/Minesweeper/Makefile
+++ b/Games/Minesweeper/Makefile
@@ -10,7 +10,7 @@ FLAVOR_FLAGS = -fno-exceptions -fno-rtti
 OPTIMIZATION_FLAGS = -Os
 INCLUDE_FLAGS = -I../.. -I. -I../../LibC
 
-DEFINES = -DSERENITY -DSANITIZE_PTRS -DUSERLAND
+DEFINES = -DSANITIZE_PTRS -DUSERLAND
 
 CXXFLAGS = -MMD -MP $(WARNING_FLAGS) $(OPTIMIZATION_FLAGS) $(FLAVOR_FLAGS) $(STANDARD_FLAGS) $(INCLUDE_FLAGS) $(DEFINES)
 CXX = i686-pc-serenity-g++
diff --git a/Games/Snake/Makefile b/Games/Snake/Makefile
index a68bd0fa5bc46e..43a4217a7e4cc4 100644
--- a/Games/Snake/Makefile
+++ b/Games/Snake/Makefile
@@ -10,7 +10,7 @@ FLAVOR_FLAGS = -fno-exceptions -fno-rtti
 OPTIMIZATION_FLAGS = -Os
 INCLUDE_FLAGS = -I../.. -I. -I../../LibC
 
-DEFINES = -DSERENITY -DSANITIZE_PTRS -DUSERLAND
+DEFINES = -DSANITIZE_PTRS -DUSERLAND
 
 CXXFLAGS = -MMD -MP $(WARNING_FLAGS) $(OPTIMIZATION_FLAGS) $(FLAVOR_FLAGS) $(STANDARD_FLAGS) $(INCLUDE_FLAGS) $(DEFINES)
 CXX = i686-pc-serenity-g++
diff --git a/Kernel/Makefile b/Kernel/Makefile
index ebd182da68aa1f..dd753ff3a01125 100644
--- a/Kernel/Makefile
+++ b/Kernel/Makefile
@@ -87,7 +87,7 @@ INCLUDE_FLAGS = -I.. -I.
 CLANG_FLAGS = -Wconsumed -m32 -ffreestanding -march=i686
 #SUGGEST_FLAGS = -Wsuggest-final-types -Wsuggest-final-methods -Wsuggest-override #-Wsuggest-attribute=noreturn 
 
-DEFINES = -DSERENITY -DKERNEL -DSANITIZE_PTRS
+DEFINES = -DKERNEL -DSANITIZE_PTRS
 
 CXXFLAGS = -MMD -MP $(WARNING_FLAGS) $(OPTIMIZATION_FLAGS) $(KERNEL_FLAGS) $(FLAVOR_FLAGS) $(ARCH_FLAGS) $(STANDARD_FLAGS) $(SUGGEST_FLAGS) $(INCLUDE_FLAGS) $(DEFINES)
 #CXX = clang $(CLANG_FLAGS)
diff --git a/Kernel/Syscall.h b/Kernel/Syscall.h
index dfaddc070d3f86..14dc789558db02 100644
--- a/Kernel/Syscall.h
+++ b/Kernel/Syscall.h
@@ -121,7 +121,7 @@ inline constexpr const char* to_string(Function function)
     return "Unknown";
 }
 
-#ifdef SERENITY
+#ifdef __serenity__
 struct SC_mmap_params {
     uint32_t addr;
     uint32_t size;
diff --git a/LibC/Makefile b/LibC/Makefile
index f6c209cfee2cf0..6986aa6a4ae119 100644
--- a/LibC/Makefile
+++ b/LibC/Makefile
@@ -55,7 +55,7 @@ FLAVOR_FLAGS = -fno-exceptions -fno-rtti -fno-sized-deallocation
 OPTIMIZATION_FLAGS = -Os
 INCLUDE_FLAGS = -I.. -I.
 
-DEFINES = -DSERENITY -DUSERLAND -DSANITIZE_PTRS
+DEFINES = -DUSERLAND -DSANITIZE_PTRS
 
 CXXFLAGS = -MMD -MP $(WARNING_FLAGS) $(OPTIMIZATION_FLAGS) $(FLAVOR_FLAGS) $(STANDARD_FLAGS) $(INCLUDE_FLAGS) $(DEFINES)
 CXX = i686-pc-serenity-g++
diff --git a/LibCore/Makefile b/LibCore/Makefile
index 8331bb64bdf55c..1d73ded45bbbe1 100644
--- a/LibCore/Makefile
+++ b/LibCore/Makefile
@@ -23,7 +23,7 @@ FLAVOR_FLAGS = -fno-exceptions -fno-rtti
 OPTIMIZATION_FLAGS = -Os
 INCLUDE_FLAGS = -I../LibC -I../Servers -I.. -I.
 
-DEFINES = -DSERENITY -DUSERLAND -DSANITIZE_PTRS -DLIBGUI
+DEFINES = -DUSERLAND -DSANITIZE_PTRS -DLIBGUI
 
 CXXFLAGS = -MMD -MP $(WARNING_FLAGS) $(OPTIMIZATION_FLAGS) $(FLAVOR_FLAGS) $(STANDARD_FLAGS) $(INCLUDE_FLAGS) $(DEFINES)
 CXX = i686-pc-serenity-g++
diff --git a/LibGUI/Makefile b/LibGUI/Makefile
index fac3de3998db19..dea0f3751b1cf3 100644
--- a/LibGUI/Makefile
+++ b/LibGUI/Makefile
@@ -61,7 +61,7 @@ FLAVOR_FLAGS = -fno-exceptions -fno-rtti
 OPTIMIZATION_FLAGS = -Os
 INCLUDE_FLAGS = -I../LibC -I../Servers -I.. -I.
 
-DEFINES = -DSERENITY -DUSERLAND -DSANITIZE_PTRS -DLIBGUI
+DEFINES = -DUSERLAND -DSANITIZE_PTRS -DLIBGUI
 
 CXXFLAGS = -MMD -MP $(WARNING_FLAGS) $(OPTIMIZATION_FLAGS) $(FLAVOR_FLAGS) $(STANDARD_FLAGS) $(INCLUDE_FLAGS) $(DEFINES)
 CXX = i686-pc-serenity-g++
diff --git a/LibM/Makefile b/LibM/Makefile
index ebc7927e3e25be..4257c41cbfd2d5 100644
--- a/LibM/Makefile
+++ b/LibM/Makefile
@@ -7,7 +7,7 @@ FLAVOR_FLAGS = -fno-exceptions -fno-rtti
 OPTIMIZATION_FLAGS = -Os
 INCLUDE_FLAGS = -I.. -I.
 
-DEFINES = -DSERENITY -DUSERLAND -DSANITIZE_PTRS
+DEFINES = -DUSERLAND -DSANITIZE_PTRS
 
 CXXFLAGS = -MMD -MP $(WARNING_FLAGS) $(OPTIMIZATION_FLAGS) $(FLAVOR_FLAGS) $(STANDARD_FLAGS) $(INCLUDE_FLAGS) $(DEFINES)
 CXX = i686-pc-serenity-g++
diff --git a/Servers/LookupServer/Makefile b/Servers/LookupServer/Makefile
index e415e01a47677c..2986a501cdec32 100644
--- a/Servers/LookupServer/Makefile
+++ b/Servers/LookupServer/Makefile
@@ -11,7 +11,7 @@ OPTIMIZATION_FLAGS = -Os
 INCLUDE_FLAGS = -I.. -I../.. -I. -I../../LibC
 LDFLAGS = -L../../LibC
 
-DEFINES = -DSERENITY -DSANITIZE_PTRS -DUSERLAND
+DEFINES = -DSANITIZE_PTRS -DUSERLAND
 
 CXXFLAGS = -MMD -MP $(WARNING_FLAGS) $(OPTIMIZATION_FLAGS) $(FLAVOR_FLAGS) $(STANDARD_FLAGS) $(INCLUDE_FLAGS) $(DEFINES)
 CXX = i686-pc-serenity-g++
diff --git a/Servers/WindowServer/Makefile b/Servers/WindowServer/Makefile
index 8c0434bf7b7bf3..6d08d3546afc00 100644
--- a/Servers/WindowServer/Makefile
+++ b/Servers/WindowServer/Makefile
@@ -36,7 +36,7 @@ OPTIMIZATION_FLAGS = -Os
 INCLUDE_FLAGS = -I.. -I../.. -I. -I../../LibC
 LDFLAGS = -L../../LibC -L../../LibCore
 
-DEFINES = -DSERENITY -DSANITIZE_PTRS -DUSERLAND
+DEFINES = -DSANITIZE_PTRS -DUSERLAND
 
 CXXFLAGS = -MMD -MP $(WARNING_FLAGS) $(OPTIMIZATION_FLAGS) $(FLAVOR_FLAGS) $(STANDARD_FLAGS) $(INCLUDE_FLAGS) $(DEFINES)
 CXX = i686-pc-serenity-g++
diff --git a/Userland/Makefile b/Userland/Makefile
index bae2fce7106dfe..22c57efa088357 100644
--- a/Userland/Makefile
+++ b/Userland/Makefile
@@ -9,7 +9,7 @@ FLAVOR_FLAGS = -fno-exceptions -fno-rtti -fno-sized-deallocation
 OPTIMIZATION_FLAGS = -Os
 INCLUDE_FLAGS = -I.. -I. -I../LibC
 
-DEFINES = -DSERENITY -DSANITIZE_PTRS -DUSERLAND
+DEFINES = -DSANITIZE_PTRS -DUSERLAND
 
 CXXFLAGS = -MMD -MP $(WARNING_FLAGS) $(OPTIMIZATION_FLAGS) $(FLAVOR_FLAGS) $(ARCH_FLAGS) $(STANDARD_FLAGS) $(INCLUDE_FLAGS) $(DEFINES)
 CXX = i686-pc-serenity-g++