diff --git a/base.cpp b/base.cpp
index 49adeb0..96f1111 100644
--- a/base.cpp
+++ b/base.cpp
@@ -139,7 +139,6 @@ typedef double   F64;
 #define JOIN(X,Y) JOIN1(X,Y)
 #define string_expand(x) (int)x.len, x.str
 
-#define CORE_STRINGS
 struct String{
   U8 *str;
   S64 len;
@@ -150,6 +149,14 @@ union Intern_String{  // Basically just String
   struct{ U8 *str; S64 len; };
 };
 
+struct Allocator {
+  typedef void *Allocate(Allocator *, size_t);
+  typedef void  Deallocate(Allocator *, void *p);
+
+  Allocate *allocate;
+  Deallocate *deallocate;
+};
+
 global String string_null = {(U8 *)"null", 4};
 #include <stdio.h>
 #define STB_SPRINTF_IMPLEMENTATION
@@ -405,10 +412,20 @@ operator!=(Intern_String a, Intern_String b){
 #define Iter_Named(list, it) for(auto it = iterate(list); should_we_continue(&it); advance(&it))
 #define Iter(list) Iter_Named(list, it)
 
-enum Alloc_Flag{
-  AF_None,
-  AF_ZeroMemory
-};
+#define allocate_array(a, T, size,...) (T *)allocate_size(a, sizeof(T)*(size),##__VA_ARGS__)
+#define allocate_struct(a, T, ...) allocate_array(a, T, 1,##__VA_ARGS__)
+CORE_Static void *allocate_size(Allocator *allocator, size_t size, bool zero_memory = true) {
+  void *result = allocator->allocate(allocator, size);
+  if (zero_memory) {
+    memory_zero(result, size);
+  }
+  return result;
+}
+
+CORE_Static void deallocate(Allocator *allocator, void *p) {
+  assert(p);
+  allocator->deallocate(allocator, p);
+}
 
 //-----------------------------------------------------------------------------
 // Memory OS
@@ -428,13 +445,12 @@ CORE_Static B32 os_decommit_pos(OS_Memory *m, size_t pos);
 global const size_t default_reserve_size   = gib(4);
 global const size_t default_alignment      = 8;
 global const size_t additional_commit_size = mib(1);
-struct Arena{
+struct Arena : Allocator {
   OS_Memory memory;
   size_t alignment;
   size_t len;
   String debug_string;
 };
-CORE_Static void arena_init(Arena *arena, String debug_name);
 
 CORE_Static void
 arena_pop_pos(Arena *arena, size_t pos){
@@ -459,15 +475,15 @@ arena_clear(Arena *arena){
   arena_pop_pos(arena, 0);
 }
 
-#define arena_push_array(a, T, size,...) (T *)arena_push_size(a, sizeof(T)*(size),##__VA_ARGS__)
-#define arena_push_type(a, T, ...) arena_push_array(a, T, 1,##__VA_ARGS__)
+CORE_Static void
+deallocate_stub(Allocator *, void *) {
+}
+
 CORE_Static void *
-arena_push_size(Arena *a, size_t size, Alloc_Flag flags = AF_None){
+arena_push_size(Arena *a, size_t size){
   size_t generous_size = size + a->alignment;
   if(a->len+generous_size>a->memory.commit){
-    if(a->memory.reserve == 0){
-      arena_init(a, "Zero initialized arena"_s);
-    }
+    assert(a->memory.reserve > 0);
     B32 result = os_commit(&a->memory, generous_size+additional_commit_size);
     assert(result);
   }
@@ -477,18 +493,16 @@ arena_push_size(Arena *a, size_t size, Alloc_Flag flags = AF_None){
   void *result = (U8*)a->memory.data + a->len;
   a->len += size;
 
-  if(flags & AF_ZeroMemory){
-    memory_zero(result, size);
-  }
-
   return result;
 }
 
 CORE_Static void
 arena_init(Arena *a, String debug_name){
-  a->memory     = os_reserve(default_reserve_size);
-  a->alignment  = default_alignment;
+  a->memory       = os_reserve(default_reserve_size);
+  a->alignment    = default_alignment;
   a->debug_string = debug_name;
+  a->allocate     = (Allocator::Allocate *)arena_push_size;
+  a->deallocate   = (Allocator::Deallocate *)deallocate_stub;
 }
 
 enum Log_Kind{Log_Kind_Normal_No_NewLine, Log_Kind_Normal, Log_Kind_Error, Log_Kind_Trace};
@@ -536,6 +550,7 @@ struct Scratch{
     arena_pop_pos(arena, saved_pos);
   }
   force_inline operator Arena*(){ return arena; }
+  force_inline operator Allocator*(){ return arena; }
 
   // @Note: Disable copy constructors, cause it caused lots of confusing errors
   //        Where it passed scratch instead of the arena into the constructor
@@ -557,7 +572,7 @@ thread_ctx_init(){
 //-----------------------------------------------------------------------------
 template<class T>
 struct Array{
-  Arena *allocator;
+  Allocator *allocator;
   T  *data;
   S64 cap;
   S64 len;
@@ -578,13 +593,14 @@ struct Array{
   void grow(S64 required_size){
     if(cap == 0){
       S64 new_cap = max(required_size*2, (S64)16);
-      data = arena_push_array(allocator, T, new_cap);
+      data = allocate_array(allocator, T, new_cap);
       cap = new_cap;
     }
     else if(len + required_size > cap){
       U64 new_cap = max(cap * 2, len+required_size+1);
-      T *new_data = arena_push_array(allocator, T, new_cap);
+      T *new_data = allocate_array(allocator, T, new_cap);
       memory_copy(new_data, data, cap*sizeof(T));
+      deallocate(allocator, data);
       data = new_data;
       cap = new_cap;
     }
@@ -622,7 +638,7 @@ struct Array{
 
   void init(Arena *a, S64 size = 16){
     allocator = a;
-    data      = arena_push_array(a, T, size);
+    data      = allocate_array(a, T, size);
     cap       = size;
   }
 
@@ -631,7 +647,7 @@ struct Array{
     result.len = len;
     result.cap = len*2;
     result.allocator = a;
-    result.data = arena_push_array(a, T, result.cap);
+    result.data = allocate_array(a, T, result.cap);
     memory_copy(result.data, data, sizeof(T)*result.len);
     return result;
   }
@@ -641,7 +657,7 @@ struct Array{
     result.len = len;
     result.cap = len;
     result.allocator = 0;
-    result.data = arena_push_array(a, T, len);
+    result.data = allocate_array(a, T, len);
     memory_copy(result.data, data, sizeof(T)*len);
     return result;
   }
@@ -731,7 +747,7 @@ struct Map_Key_Value{
 };
 
 struct Map{
-  Arena *allocator;
+  Allocator *allocator;
   Map_Key_Value *data;
   S64 len;
   S64 cap;
@@ -746,7 +762,7 @@ map_grow(Map *map, S64 new_size){
   assert(map->allocator);
 
   Map new_map       = {};
-  new_map.data      = arena_push_array(map->allocator, Map_Key_Value, new_size, AF_ZeroMemory);
+  new_map.data      = allocate_array(map->allocator, Map_Key_Value, new_size);
   new_map.cap       = new_size;
   new_map.allocator = map->allocator;
 
@@ -755,7 +771,7 @@ map_grow(Map *map, S64 new_size){
       map_insert(&new_map, map->data[i].key, map->data[i].value);
     }
   }
-  // if(map->data) exp_free(map->allocator, map->data);
+  if(map->data) deallocate(map->allocator, map->data);
   *map = new_map;
 }
 
diff --git a/base_string.cpp b/base_string.cpp
index 8b5e04f..24d7c4d 100644
--- a/base_string.cpp
+++ b/base_string.cpp
@@ -77,7 +77,7 @@ operator==(String a, String b){
 
 CORE_Static String
 string_copy(Arena *a, String string){
-  U8 *copy = arena_push_array(a, U8, string.len+1);
+  U8 *copy = allocate_array(a, U8, string.len+1);
   memory_copy(copy, string.str, string.len);
   copy[string.len] = 0;
   return String{copy, string.len};
@@ -90,7 +90,7 @@ string_fmtv(Arena *a, const char *str, va_list args1) {
   S64 len = stbsp_vsnprintf(0, 0, str, args2);
   va_end(args2);
 
-  char *result = arena_push_array(a, char, len + 1);
+  char *result = allocate_array(a, char, len + 1);
   stbsp_vsnprintf(result, len + 1, str, args1);
 
   String res = {(U8 *)result, len};
diff --git a/base_unicode.cpp b/base_unicode.cpp
index 272827d..2593ca2 100644
--- a/base_unicode.cpp
+++ b/base_unicode.cpp
@@ -160,7 +160,7 @@ utf16_to_utf32(U16 *c, S32 max_advance) {
 
 CORE_Static String32
 string16_to_string32(Arena *allocator, String16 string){
-  String32 result = {arena_push_array(allocator, U32, string.len+1)};
+  String32 result = {allocate_array(allocator, U32, string.len+1)};
   for(S64 i = 0; i < string.len;){
     UTF32_Result decode = utf16_to_utf32(string.str + i, string.len - i);
     if(!decode.error){
@@ -176,7 +176,7 @@ string16_to_string32(Arena *allocator, String16 string){
 
 CORE_Static String32
 string8_to_string32(Arena *allocator, String string){
-  String32 result = {arena_push_array(allocator, U32, string.len+1)};
+  String32 result = {allocate_array(allocator, U32, string.len+1)};
   for(S64 i = 0; i < string.len;){
     UTF32_Result decode = utf8_to_utf32(string.str + i, string.len - i);
     if(!decode.error){
@@ -191,7 +191,7 @@ string8_to_string32(Arena *allocator, String string){
 
 CORE_Static String16
 string8_to_string16(Arena *allocator, String in){
-  String16 result = {arena_push_array(allocator, U16, (in.len*2)+1)}; // @Note(Krzosa): Should be more then enough space
+  String16 result = {allocate_array(allocator, U16, (in.len*2)+1)}; // @Note(Krzosa): Should be more then enough space
   for(S64 i = 0; i < in.len;){
     UTF32_Result decode = utf8_to_utf32(in.str + i, in.len - i);
     if(!decode.error){
@@ -213,7 +213,7 @@ string8_to_string16(Arena *allocator, String in){
 
 CORE_Static String
 string16_to_string8(Arena *allocator, String16 in){
-  String result = {arena_push_array(allocator, U8, in.len*4+1)};
+  String result = {allocate_array(allocator, U8, in.len*4+1)};
   for(S64 i = 0; i < in.len;){
     UTF32_Result decode = utf16_to_utf32(in.str + i, in.len - i);
     if(!decode.error){
@@ -267,7 +267,7 @@ string16_from_widechar(wchar_t *string){
 
 CORE_Static String
 string16_copy(Arena *a, String string){
-  U8 *copy = arena_push_array(a, U8, string.len+1);
+  U8 *copy = allocate_array(a, U8, string.len+1);
   memory_copy(copy, string.str, string.len);
   copy[string.len] = 0;
   return String{copy, string.len};
diff --git a/c3_big_int.cpp b/c3_big_int.cpp
index 642d211..66f457d 100644
--- a/c3_big_int.cpp
+++ b/c3_big_int.cpp
@@ -55,7 +55,7 @@ bigint_copy(Arena *allocator, BigInt *src){
   dest.digit_count = src->digit_count;
 
   count_bigint_alloc();
-  dest.digits = arena_push_array(allocator, uint64_t, dest.digit_count, AF_ZeroMemory);
+  dest.digits = allocate_array(allocator, uint64_t, dest.digit_count);
   memcpy(dest.digits, src->digits, sizeof(uint64_t) * dest.digit_count);
   return dest;
 }
diff --git a/c3_big_int.h b/c3_big_int.h
index 3f5ff3a..18d7bf9 100644
--- a/c3_big_int.h
+++ b/c3_big_int.h
@@ -9,7 +9,7 @@ enum CmpRes
 };
 
 #define count_bigint_alloc() (bigint_allocator != thread_ctx.scratch ? bigint_allocation_count++ : 0)
-#define malloc_arena(x) (count_bigint_alloc(), arena_push_size(bigint_allocator, x, AF_ZeroMemory))
+#define malloc_arena(x) (count_bigint_alloc(), allocate_size(bigint_allocator, x))
 #define ALLOC_DIGITS(_digits) (uint64_t *)((_digits) ? malloc_arena(sizeof(uint64_t) * (_digits)) : NULL)
 #define FATAL_ERROR(x) compiler_error(0, x)
 
diff --git a/core_ast.cpp b/core_ast.cpp
index d72fcc8..13ba4cf 100644
--- a/core_ast.cpp
+++ b/core_ast.cpp
@@ -1,7 +1,7 @@
 
 
 #define AST_NEW(T,ikind,ipos,iflags)                                   \
-  Ast_##T *result = arena_push_type(pctx->perm, Ast_##T, AF_ZeroMemory);\
+  Ast_##T *result = allocate_struct(pctx->perm, Ast_##T);              \
   result->flags   = iflags;                                            \
   result->kind    = AST_##ikind;                                       \
   result->parent_scope = pctx->currently_parsed_scope;                 \
@@ -11,7 +11,7 @@
 #define ast_new(T,kind,pos,flags) (T *)_ast_new(sizeof(T), kind, pos, flags)
 CORE_Static Ast *
 _ast_new(size_t size, Ast_Kind kind, Token *pos, Ast_Flag flags = 0){
-  Ast *result = (Ast *)arena_push_size(pctx->perm, size, AF_ZeroMemory);
+  Ast *result = (Ast *)allocate_size(pctx->perm, size);
   result->flags   = flags;
   result->kind    = kind;
   result->parent_scope = pctx->currently_parsed_scope;
diff --git a/core_compiler.cpp b/core_compiler.cpp
index 58fc5ec..9d95529 100644
--- a/core_compiler.cpp
+++ b/core_compiler.cpp
@@ -98,7 +98,7 @@ parse_init(Parse_Ctx *ctx, Arena *perm_allocator) {
 CORE_Static void
 begin_compilation() {
   init_ctx_time_begin = os_time();
-  Parse_Ctx *ctx      = arena_push_type(&pernament_arena, Parse_Ctx, AF_ZeroMemory);
+  Parse_Ctx *ctx      = allocate_struct(&pernament_arena, Parse_Ctx);
   parse_init(ctx, &pernament_arena);
   init_ctx_time_end = os_time();
 }
diff --git a/core_compiler.h b/core_compiler.h
index 8c6a8d5..7f0be47 100644
--- a/core_compiler.h
+++ b/core_compiler.h
@@ -20,6 +20,7 @@ struct Lexer{
   U32 token_debug_ids;
 
   Intern_String intern(String string){
+    assert(string.len > 0);
     return intern_string(&interns, string);
   }
 };
diff --git a/core_compiler_interface.hpp b/core_compiler_interface.hpp
index 7120e3b..5578a36 100644
--- a/core_compiler_interface.hpp
+++ b/core_compiler_interface.hpp
@@ -13,6 +13,15 @@ struct Ast_Expr;
 
 #ifndef CORE_BASE
 #define CORE_BASE
+
+struct Allocator {
+  typedef void *Allocate(Allocator *, size_t);
+  typedef void  Deallocate(Allocator *, void *p);
+
+  Allocate *allocate;
+  Deallocate *deallocate;
+};
+
 struct String{
   uint8_t *str;
   int64_t len;
diff --git a/core_main.cpp b/core_main.cpp
index 21440f7..41ca13d 100644
--- a/core_main.cpp
+++ b/core_main.cpp
@@ -286,6 +286,8 @@ For modules it's a bit different cause they should be distributed as valid.
 
 
 int main(int argument_count, char **arguments){
+  thread_ctx_init();
+
   Scratch scratch;
   Array<String> args = {scratch};
   for(int i = 1; i < argument_count; i+=1){
@@ -326,7 +328,6 @@ int main(int argument_count, char **arguments){
   test_os_memory();
 #endif
 
-  thread_ctx_init();
   test_unicode();
 
   map_test();
diff --git a/core_types.cpp b/core_types.cpp
index 249641e..a39a29d 100644
--- a/core_types.cpp
+++ b/core_types.cpp
@@ -59,7 +59,7 @@ force_inline B32 is_numeric(Ast_Type *type){
 //-----------------------------------------------------------------------------
 CORE_Static Ast_Type *
 type_new(Arena *allocator, Ast_Type_Kind kind, size_t size, size_t align){
-  Ast_Type *result  = arena_push_type(allocator, Ast_Type, AF_ZeroMemory);
+  Ast_Type *result  = allocate_struct(allocator, Ast_Type, true);
   result->kind  = kind;
   result->size  = size;
   result->align = align;
@@ -71,7 +71,7 @@ type_new(Arena *allocator, Ast_Type_Kind kind, size_t size, size_t align){
 CORE_Static Ast_Type *
 type_copy(Arena *a, Ast_Type *type){
   // @warning: This changes type id !!!!
-  Ast_Type *result = arena_push_type(a, Ast_Type);
+  Ast_Type *result = allocate_struct(a, Ast_Type);
   memory_copy(result, type, sizeof(Ast_Type));
   result->type_id = pctx->type_ids++;
   add(pctx->perm, &pctx->all_types, result);
diff --git a/os_windows.cpp b/os_windows.cpp
index 725a0f3..6d7a315 100644
--- a/os_windows.cpp
+++ b/os_windows.cpp
@@ -162,7 +162,7 @@ os_get_absolute_path(Arena *a, String path){
   Scratch scratch(a);
   String16 path16 = string8_to_string16(scratch, path);
 
-  wchar_t *buffer = arena_push_array(scratch, wchar_t, 2048);
+  wchar_t *buffer = allocate_array(scratch, wchar_t, 2048);
   DWORD written = GetFullPathNameW((wchar_t *)path16.str, 2048, buffer, 0);
   if(written == 0) return {};