diff --git a/gebs.h b/gebs.h
index cd856a3..56bbc8d 100644
--- a/gebs.h
+++ b/gebs.h
@@ -95,6 +95,17 @@ int main(int argc, char ** argv)
 #include <sys/wait.h>
 #include <sys/mman.h>
 
+// ----------------------------------------------------------------------------
+// Types
+// ----------------------------------------------------------------------------
+
+#define nil ((void *)0)
+
+typedef unsigned char       uchar;
+typedef unsigned short      ushort;
+typedef unsigned int        uint;
+typedef unsigned long long  vlong;
+
 #define discard __attribute__((unused))
 
 // ----------------------------------------------------------------------------
@@ -199,7 +210,7 @@ void gebs_arena_destroy_chunk(Gebs_Arena_Chunk *chunk);
 
 #define gebs_list_append_alloc(alloc, list, item) \
     do { \
-        if ((list)->items == NULL) { \
+        if ((list)->items == nil) { \
             (list)->capacity = 1; \
             (list)->items = gebs_malloc((alloc), \
                                        sizeof(*(list)->items) * (list)->capacity); \
@@ -220,9 +231,9 @@ void gebs_arena_destroy_chunk(Gebs_Arena_Chunk *chunk);
 
 #define gebs_list_free_alloc(alloc, list) \
     do { \
-        if ((list)->items != NULL) { \
+        if ((list)->items != nil) { \
             gebs_free((alloc), (list)->items); \
-            (list)->items = NULL; \
+            (list)->items = nil; \
         } \
         (list)->count = 0; \
     } while(0)
@@ -352,7 +363,7 @@ void gebs_rebuild_self1_alloc(Gebs_Allocator *alloc, int argc, char ** argv,
             const char *__flags[] = { __VA_ARGS__ }; \
             FILE *__out = fopen("compile_flags.txt", "w"); \
             char __nl = '\n'; \
-            if (__out != NULL) { \
+            if (__out != nil) { \
                 for (size_t __i = 0; __i < sizeof(__flags)/sizeof(__flags[0]); __i++) { \
                     const char *__flag = __flags[__i]; \
                     fwrite(__flag, strlen(__flag), 1, __out); \
@@ -393,7 +404,7 @@ int gebs_cmd_run_sync_alloc(Gebs_Allocator *alloc, Gebs_Cmd *cmd)
     for (size_t i = 0; i < cmd->count; i++) {
         gebs_cmd_append_alloc(alloc, &new_cmd, cmd->items[i]);
     }
-    gebs_cmd_append_alloc((alloc), &new_cmd, NULL);
+    gebs_cmd_append_alloc((alloc), &new_cmd, nil);
 
     pid_t pid = vfork();
     switch (pid) {
@@ -437,7 +448,7 @@ int gebs_cmd_run_sync_collect_alloc(Gebs_Allocator *alloc, Gebs_Cmd *cmd, Gebs_S
     for (size_t i = 0; i < cmd->count; i++) {
         gebs_cmd_append_alloc(alloc, &new_cmd, cmd->items[i]);
     }
-    gebs_cmd_append_alloc((alloc), &new_cmd, NULL);
+    gebs_cmd_append_alloc((alloc), &new_cmd, nil);
 
     int pipe_ends[2];
     pipe(pipe_ends);
@@ -515,7 +526,7 @@ Gebs_Arena_Chunk *gebs_arena_create_chunk(size_t capacity)
 {
     size_t size = sizeof(Gebs_Arena_Chunk) + sizeof(uintptr_t)*capacity;
     Gebs_Arena_Chunk *chunk = (Gebs_Arena_Chunk *)malloc(size);
-    chunk->next = NULL;
+    chunk->next = nil;
     chunk->size = 0;
     chunk->capacity = capacity;
     return chunk;
@@ -532,7 +543,7 @@ void *gebs_arena_malloc(void *self, size_t size)
     
     size_t sz = (size + sizeof(uintptr_t) - 1)/sizeof(uintptr_t);
 
-    if (a->end == NULL) {
+    if (a->end == nil) {
         size_t capacity = GEBS_ARENA_CHUNK_CAPACITY;
         if (capacity < sz) {
             capacity = sz;
@@ -541,7 +552,7 @@ void *gebs_arena_malloc(void *self, size_t size)
         a->begin = a->end;
     }
 
-    while (a->end->size + sz > a->end->capacity && a->end->next != NULL) {
+    while (a->end->size + sz > a->end->capacity && a->end->next != nil) {
         a->end = a->end->next;
     }
 
@@ -581,7 +592,7 @@ void *gebs_arena_realloc(void *self, void *memory,
 
 void gebs_arena_reset(Gebs_Arena *a)
 {
-    for (Gebs_Arena_Chunk *chunk = a->begin; chunk != NULL; chunk = chunk->next) {
+    for (Gebs_Arena_Chunk *chunk = a->begin; chunk != nil; chunk = chunk->next) {
         chunk->size = 0;
     }
     a->end = a->begin;
@@ -595,8 +606,8 @@ void gebs_arena_destroy(Gebs_Arena *a)
         chunk = chunk->next;
         gebs_arena_destroy_chunk(chunk1);
     }
-    a->begin = NULL;
-    a->end = NULL;
+    a->begin = nil;
+    a->end = nil;
 }
 
 // ----------------------------------------------------------------------------
@@ -624,7 +635,7 @@ char *gebs_fmt(const char *fmt, ...)
 
     va_list list_copy;
     va_copy(list_copy, list);
-    size_t size = vsnprintf(NULL, 0, fmt, list_copy);
+    size_t size = vsnprintf(nil, 0, fmt, list_copy);
     va_end(list_copy);
 
     char *buf = gebs_malloc(&gebs_scratch_arena, size+1);