diff --git a/AK/AKString.h b/AK/AKString.h
index 742913167d8..7784c9252f9 100644
--- a/AK/AKString.h
+++ b/AK/AKString.h
@@ -59,7 +59,7 @@ public:
     {
     }
 
-    String(const char* cstring, ssize_t length, ShouldChomp shouldChomp = NoChomp)
+    String(const char* cstring, int length, ShouldChomp shouldChomp = NoChomp)
         : m_impl(StringImpl::create(cstring, length, shouldChomp))
     {
     }
@@ -118,9 +118,9 @@ public:
 
     bool is_null() const { return !m_impl; }
     bool is_empty() const { return length() == 0; }
-    ssize_t length() const { return m_impl ? m_impl->length() : 0; }
+    int length() const { return m_impl ? m_impl->length() : 0; }
     const char* characters() const { return m_impl ? m_impl->characters() : nullptr; }
-    char operator[](ssize_t i) const
+    char operator[](int i) const
     {
         ASSERT(m_impl);
         return (*m_impl)[i];
diff --git a/AK/ByteBuffer.h b/AK/ByteBuffer.h
index c472e940224..1f866ed5e54 100644
--- a/AK/ByteBuffer.h
+++ b/AK/ByteBuffer.h
@@ -100,12 +100,12 @@ public:
         return *this;
     }
 
-    static ByteBuffer create_uninitialized(ssize_t size) { return ByteBuffer(ByteBufferImpl::create_uninitialized(size)); }
-    static ByteBuffer create_zeroed(ssize_t size) { return ByteBuffer(ByteBufferImpl::create_zeroed(size)); }
-    static ByteBuffer copy(const void* data, ssize_t size) { return ByteBuffer(ByteBufferImpl::copy(data, size)); }
-    static ByteBuffer wrap(const void* data, ssize_t size) { return ByteBuffer(ByteBufferImpl::wrap(data, size)); }
-    static ByteBuffer wrap(void* data, ssize_t size) { return ByteBuffer(ByteBufferImpl::wrap(data, size)); }
-    static ByteBuffer adopt(void* data, ssize_t size) { return ByteBuffer(ByteBufferImpl::adopt(data, size)); }
+    static ByteBuffer create_uninitialized(int size) { return ByteBuffer(ByteBufferImpl::create_uninitialized(size)); }
+    static ByteBuffer create_zeroed(int size) { return ByteBuffer(ByteBufferImpl::create_zeroed(size)); }
+    static ByteBuffer copy(const void* data, int size) { return ByteBuffer(ByteBufferImpl::copy(data, size)); }
+    static ByteBuffer wrap(const void* data, int size) { return ByteBuffer(ByteBufferImpl::wrap(data, size)); }
+    static ByteBuffer wrap(void* data, int size) { return ByteBuffer(ByteBufferImpl::wrap(data, size)); }
+    static ByteBuffer adopt(void* data, int size) { return ByteBuffer(ByteBufferImpl::adopt(data, size)); }
 
     ~ByteBuffer() { clear(); }
     void clear() { m_impl = nullptr; }
@@ -114,18 +114,18 @@ public:
     bool operator!() const { return is_null(); }
     bool is_null() const { return m_impl == nullptr; }
 
-    byte& operator[](ssize_t i)
+    byte& operator[](int i)
     {
         ASSERT(m_impl);
         return (*m_impl)[i];
     }
-    byte operator[](ssize_t i) const
+    byte operator[](int i) const
     {
         ASSERT(m_impl);
         return (*m_impl)[i];
     }
     bool is_empty() const { return !m_impl || m_impl->is_empty(); }
-    ssize_t size() const { return m_impl ? m_impl->size() : 0; }
+    int size() const { return m_impl ? m_impl->size() : 0; }
 
     byte* data() { return pointer(); }
     const byte* data() const { return pointer(); }
@@ -133,8 +133,8 @@ public:
     byte* pointer() { return m_impl ? m_impl->pointer() : nullptr; }
     const byte* pointer() const { return m_impl ? m_impl->pointer() : nullptr; }
 
-    byte* offset_pointer(ssize_t offset) { return m_impl ? m_impl->offset_pointer(offset) : nullptr; }
-    const byte* offset_pointer(ssize_t offset) const { return m_impl ? m_impl->offset_pointer(offset) : nullptr; }
+    byte* offset_pointer(int offset) { return m_impl ? m_impl->offset_pointer(offset) : nullptr; }
+    const byte* offset_pointer(int offset) const { return m_impl ? m_impl->offset_pointer(offset) : nullptr; }
 
     void* end_pointer() { return m_impl ? m_impl->end_pointer() : nullptr; }
     const void* end_pointer() const { return m_impl ? m_impl->end_pointer() : nullptr; }
@@ -147,13 +147,13 @@ public:
     }
 
     // NOTE: trim() does not reallocate.
-    void trim(ssize_t size)
+    void trim(int size)
     {
         if (m_impl)
             m_impl->trim(size);
     }
 
-    ByteBuffer slice(ssize_t offset, ssize_t size) const
+    ByteBuffer slice(int offset, int size) const
     {
         if (is_null())
             return {};
@@ -164,7 +164,7 @@ public:
         return copy(offset_pointer(offset), size);
     }
 
-    void grow(ssize_t size)
+    void grow(int size)
     {
         if (!m_impl)
             m_impl = ByteBufferImpl::create_uninitialized(size);
@@ -204,7 +204,7 @@ inline ByteBufferImpl::ByteBufferImpl(const void* data, int size, ConstructionMo
     m_owned = true;
 }
 
-inline ByteBufferImpl::ByteBufferImpl(void* data, ssize_t size, ConstructionMode mode)
+inline ByteBufferImpl::ByteBufferImpl(void* data, int size, ConstructionMode mode)
     : m_data(static_cast<byte*>(data))
     , m_size(size)
 {
@@ -215,7 +215,7 @@ inline ByteBufferImpl::ByteBufferImpl(void* data, ssize_t size, ConstructionMode
     }
 }
 
-inline void ByteBufferImpl::grow(ssize_t size)
+inline void ByteBufferImpl::grow(int size)
 {
     ASSERT(size > m_size);
     ASSERT(m_owned);
diff --git a/AK/PrintfImplementation.h b/AK/PrintfImplementation.h
index 0088b550cef..087eb34d437 100644
--- a/AK/PrintfImplementation.h
+++ b/AK/PrintfImplementation.h
@@ -1,11 +1,15 @@
 #pragma once
 
 #include <AK/Types.h>
-#include <LibC/stdarg.h>
+#include <stdarg.h>
 
 static constexpr const char* printf_hex_digits = "0123456789abcdef";
 
+#ifdef __serenity__
 extern "C" size_t strlen(const char*);
+#else
+#include <string.h>
+#endif
 
 template<typename PutChFunc, typename T>
 [[gnu::always_inline]] inline int print_hex(PutChFunc putch, char*& bufptr, T number, byte fields)
@@ -174,7 +178,7 @@ template<typename PutChFunc>
 }
 
 template<typename PutChFunc>
-[[gnu::always_inline]] inline int printf_internal(PutChFunc putch, char* buffer, const char*& fmt, char*& ap)
+[[gnu::always_inline]] inline int printf_internal(PutChFunc putch, char* buffer, const char*& fmt, va_list ap)
 {
     const char* p;
 
diff --git a/AK/String.cpp b/AK/String.cpp
index d0ca1b49095..fce8006e4d6 100644
--- a/AK/String.cpp
+++ b/AK/String.cpp
@@ -1,7 +1,7 @@
 #include "AKString.h"
 #include "StdLibExtras.h"
 #include "StringBuilder.h"
-#include <LibC/stdarg.h>
+#include <stdarg.h>
 
 namespace AK {
 
@@ -78,17 +78,17 @@ Vector<String> String::split_limit(const char separator, int limit) const
         return {};
 
     Vector<String> v;
-    ssize_t substart = 0;
-    for (ssize_t i = 0; i < length() && (v.size() + 1) != limit; ++i) {
+    int substart = 0;
+    for (int i = 0; i < length() && (v.size() + 1) != limit; ++i) {
         char ch = characters()[i];
         if (ch == separator) {
-            ssize_t sublen = i - substart;
+            int sublen = i - substart;
             if (sublen != 0)
                 v.append(substring(substart, sublen));
             substart = i + 1;
         }
     }
-    ssize_t taillen = length() - substart;
+    int taillen = length() - substart;
     if (taillen != 0)
         v.append(substring(substart, taillen));
     if (characters()[length() - 1] == separator)
@@ -102,17 +102,17 @@ Vector<StringView> String::split_view(const char separator) const
         return {};
 
     Vector<StringView> v;
-    ssize_t substart = 0;
-    for (ssize_t i = 0; i < length(); ++i) {
+    int substart = 0;
+    for (int i = 0; i < length(); ++i) {
         char ch = characters()[i];
         if (ch == separator) {
-            ssize_t sublen = i - substart;
+            int sublen = i - substart;
             if (sublen != 0)
                 v.append(substring_view(substart, sublen));
             substart = i + 1;
         }
     }
-    ssize_t taillen = length() - substart;
+    int taillen = length() - substart;
     if (taillen != 0)
         v.append(substring_view(substart, taillen));
     if (characters()[length() - 1] == separator)
@@ -131,7 +131,7 @@ int String::to_int(bool& ok) const
 {
     bool negative = false;
     int value = 0;
-    ssize_t i = 0;
+    int i = 0;
 
     if (is_null()) {
         ok = false;
@@ -158,7 +158,7 @@ int String::to_int(bool& ok) const
 unsigned String::to_uint(bool& ok) const
 {
     unsigned value = 0;
-    for (ssize_t i = 0; i < length(); ++i) {
+    for (int i = 0; i < length(); ++i) {
         if (characters()[i] < '0' || characters()[i] > '9') {
             ok = false;
             return 0;
diff --git a/AK/StringBuilder.cpp b/AK/StringBuilder.cpp
index 6ba5754c73f..429bb5771b1 100644
--- a/AK/StringBuilder.cpp
+++ b/AK/StringBuilder.cpp
@@ -1,17 +1,17 @@
 #include <AK/PrintfImplementation.h>
 #include <AK/StdLibExtras.h>
 #include <AK/StringBuilder.h>
-#include <LibC/stdarg.h>
+#include <stdarg.h>
 
 namespace AK {
 
-inline void StringBuilder::will_append(ssize_t size)
+inline void StringBuilder::will_append(int size)
 {
     if ((m_length + size) > m_buffer.size())
-        m_buffer.grow(max((ssize_t)16, m_buffer.size() * 2 + size));
+        m_buffer.grow(max((int)16, m_buffer.size() * 2 + size));
 }
 
-StringBuilder::StringBuilder(ssize_t initial_capacity)
+StringBuilder::StringBuilder(int initial_capacity)
 {
     m_buffer.grow(initial_capacity);
 }
@@ -25,7 +25,7 @@ void StringBuilder::append(const StringView& str)
     m_length += str.length();
 }
 
-void StringBuilder::append(const char* characters, ssize_t length)
+void StringBuilder::append(const char* characters, int length)
 {
     if (!length)
         return;
diff --git a/AK/StringBuilder.h b/AK/StringBuilder.h
index 65bc8e2c072..744c71ef4b2 100644
--- a/AK/StringBuilder.h
+++ b/AK/StringBuilder.h
@@ -2,18 +2,18 @@
 
 #include "AKString.h"
 #include "Vector.h"
-#include <LibC/stdarg.h>
+#include <stdarg.h>
 
 namespace AK {
 
 class StringBuilder {
 public:
-    explicit StringBuilder(ssize_t initial_capacity = 16);
+    explicit StringBuilder(int initial_capacity = 16);
     ~StringBuilder() {}
 
     void append(const StringView&);
     void append(char);
-    void append(const char*, ssize_t);
+    void append(const char*, int);
     void appendf(const char*, ...);
     void appendvf(const char*, va_list);
 
@@ -21,10 +21,10 @@ public:
     ByteBuffer to_byte_buffer();
 
 private:
-    void will_append(ssize_t);
+    void will_append(int);
 
     ByteBuffer m_buffer;
-    ssize_t m_length { 0 };
+    int m_length { 0 };
 };
 
 }
diff --git a/AK/StringImpl.cpp b/AK/StringImpl.cpp
index 2799e237d6d..0130cb90bad 100644
--- a/AK/StringImpl.cpp
+++ b/AK/StringImpl.cpp
@@ -3,6 +3,10 @@
 #include "StdLibExtras.h"
 #include "kmalloc.h"
 
+#ifndef __serenity__
+#include <new>
+#endif
+
 //#define DEBUG_STRINGIMPL
 
 #ifdef DEBUG_STRINGIMPL
diff --git a/AK/Vector.h b/AK/Vector.h
index c1b9c5622f0..12131ae9584 100644
--- a/AK/Vector.h
+++ b/AK/Vector.h
@@ -4,6 +4,10 @@
 #include <AK/StdLibExtras.h>
 #include <AK/kmalloc.h>
 
+#ifndef __serenity__
+#include <new>
+#endif
+
 namespace AK {
 
 template<typename T, int inline_capacity = 0>