diff --git a/samples/c_code_generation.c b/samples/c_code_generation.c
index 454d9c3..25264ce 100644
--- a/samples/c_code_generation.c
+++ b/samples/c_code_generation.c
@@ -11,9 +11,6 @@ static MD_Arena *arena = 0;
 
 int main(int argument_count, char **arguments)
 {
-    MD_ThreadContext tctx;
-    MD_ThreadInit(&tctx);
-    
     arena = MD_ArenaAlloc(1ull << 40);
     
     MD_String8 example_code = MD_S8Lit("@struct Foo:\n"
diff --git a/samples/node_errors/node_errors.c b/samples/node_errors/node_errors.c
index c0153c2..742733e 100644
--- a/samples/node_errors/node_errors.c
+++ b/samples/node_errors/node_errors.c
@@ -7,9 +7,6 @@ static MD_Arena *arena = 0;
 
 int main(int argument_count, char **arguments)
 {
-    MD_ThreadContext tctx;
-    MD_ThreadInit(&tctx);
-    
     arena = MD_ArenaAlloc(1ull << 40);
     
     // NOTE(rjf): Parse all the files passed in via command line.
diff --git a/samples/old_style_custom_layer.c b/samples/old_style_custom_layer.c
index 94bf681..1e710ae 100644
--- a/samples/old_style_custom_layer.c
+++ b/samples/old_style_custom_layer.c
@@ -25,9 +25,6 @@ CleanUp(void)
 
 int main(int argument_count, char **arguments)
 {
-    MD_ThreadContext tctx;
-    MD_ThreadInit(&tctx);
-    
     arena = MD_ArenaAlloc(1ull << 40);
     
     // NOTE(rjf): Parse all the files passed in via command line.
diff --git a/samples/output_parse/output_parse.c b/samples/output_parse/output_parse.c
index 587a266..4e6959e 100644
--- a/samples/output_parse/output_parse.c
+++ b/samples/output_parse/output_parse.c
@@ -64,9 +64,6 @@ static void PrintNode(MD_Node* node, FILE* file, int indent_count) {
 
 int main(int argument_count, char **arguments)
 {
-    MD_ThreadContext tctx;
-    MD_ThreadInit(&tctx);
-    
     arena = MD_ArenaAlloc(1ull << 40);
     
     // NOTE(pmh): Parse all the files passed in via command line.
diff --git a/samples/parse_check.c b/samples/parse_check.c
index 6dcd20f..b342992 100644
--- a/samples/parse_check.c
+++ b/samples/parse_check.c
@@ -5,9 +5,6 @@ static MD_Arena *arena = 0;
 
 int main(int argument_count, char **arguments)
 {
-    MD_ThreadContext tctx;
-    MD_ThreadInit(&tctx);
-    
     arena = MD_ArenaAlloc(1ull << 40);
     
     MD_Node *list = MD_MakeList(arena);
diff --git a/samples/static_site_generator/static_site_generator.c b/samples/static_site_generator/static_site_generator.c
index 8893c4e..9de4d2f 100644
--- a/samples/static_site_generator/static_site_generator.c
+++ b/samples/static_site_generator/static_site_generator.c
@@ -34,9 +34,6 @@ static MD_Arena *arena = 0;
 
 int main(int argument_count, char **arguments)
 {
-    MD_ThreadContext tctx;
-    MD_ThreadInit(&tctx);
-    
     arena = MD_ArenaAlloc(1ull << 40);
     
     //~ NOTE(rjf): Parse command line arguments.
diff --git a/samples/toy_language/toy_language.c b/samples/toy_language/toy_language.c
index 7e8b691..76c610c 100644
--- a/samples/toy_language/toy_language.c
+++ b/samples/toy_language/toy_language.c
@@ -182,9 +182,6 @@ EvaluateScope(NamespaceNode *ns, MD_Node *code)
 
 int main(int argument_count, char **arguments)
 {
-    MD_ThreadContext tctx;
-    MD_ThreadInit(&tctx);
-    
     arena = MD_ArenaAlloc(1ull << 40);
     
     //- rjf: parse command line
diff --git a/source/md.c b/source/md.c
index 7acb786..fc91a8d 100644
--- a/source/md.c
+++ b/source/md.c
@@ -217,6 +217,7 @@ MD_LINUX_FileIterIncrement(MD_Arena *arena, MD_FileIter *opaque_it, MD_String8 p
 
 #if MD_DEFAULT_ARENA
 
+//- "low level memory" implementation check
 #if !defined(MD_IMPL_Reserve)
 # error Missing implementation for MD_IMPL_Reserve
 #endif
@@ -295,6 +296,78 @@ MD_ArenaDefaultPopTo(MD_ArenaDefault *arena, MD_u64 pos){
 
 #endif
 
+//- "arena" implementation checks
+#if !defined(MD_IMPL_ArenaAlloc)
+# error Missing implementation for MD_IMPL_ArenaAlloc
+#endif
+#if !defined(MD_IMPL_ArenaRelease)
+# error Missing implementation for MD_IMPL_ArenaRelease
+#endif
+#if !defined(MD_IMPL_ArenaGetPos)
+# error Missing implementation for MD_IMPL_ArenaGetPos
+#endif
+#if !defined(MD_IMPL_ArenaPush)
+# error Missing implementation for MD_IMPL_ArenaPush
+#endif
+#if !defined(MD_IMPL_ArenaPopTo)
+# error Missing implementation for MD_IMPL_ArenaPopTo
+#endif
+#if !defined(MD_IMPL_ArenaSetAutoAlign)
+# error Missing implementation for MD_IMPL_ArenaSetAutoAlign
+#endif
+#if !defined(MD_IMPL_ArenaHeaderSize)
+# error Missing implementation for MD_IMPL_ArenaHeaderSize
+#endif
+
+//~/////////////////////////////////////////////////////////////////////////////
+///////////////////////////// MD Scratch Pool //////////////////////////////////
+////////////////////////////////////////////////////////////////////////////////
+
+#if MD_DEFAULT_SCRATCH
+
+#if !defined(MD_IMPL_ScratchSize)
+# define MD_IMPL_ScratchSize (1llu << 30)
+#endif
+#if !defined(MD_IMPL_ScratchCount)
+# define MD_IMPL_ScratchCount 2llu
+#endif
+
+#if !defined(MD_IMPL_GetScratch)
+# define MD_IMPL_GetScratch MD_GetScratchDefault
+#endif
+
+MD_THREAD_LOCAL MD_Arena *md_thread_scratch_pool[MD_IMPL_ScratchCount] = {0, 0};
+
+static MD_Arena*
+MD_GetScratchDefault(MD_Arena **conflicts, MD_u64 count){
+    MD_Arena **scratch_pool = md_thread_scratch_pool;
+    if (scratch_pool[0] == 0){
+        MD_Arena **arena_ptr = scratch_pool;
+        for (MD_u64 i = 0; i < MD_IMPL_ScratchCount; i += 1, arena_ptr += 1){
+            *arena_ptr = MD_ArenaAlloc(MD_IMPL_ScratchSize);
+        }
+    }
+    MD_Arena *result = 0;
+    MD_Arena **arena_ptr = scratch_pool;
+    for (MD_u64 i = 0; i < MD_IMPL_ScratchCount; i += 1, arena_ptr += 1){
+        MD_Arena *arena = *arena_ptr;
+        MD_Arena **conflict_ptr = conflicts;
+        for (MD_u32 j = 0; j < count; j += 1, conflict_ptr += 1){
+            if (arena == *conflict_ptr){
+                arena = 0;
+                break;
+            }
+        }
+        if (arena != 0){
+            result = arena;
+            break;
+        }
+    }
+    return(result);
+}
+
+#endif
+
 //~/////////////////////////////////////////////////////////////////////////////
 //////////////////////// MD Library Implementation /////////////////////////////
 ////////////////////////////////////////////////////////////////////////////////
@@ -347,28 +420,6 @@ MD_MemoryCopy(void *dest, void *src, MD_u64 size)
 
 //~ Arena Functions
 
-#if !defined(MD_IMPL_ArenaAlloc)
-# error Missing implementation for MD_IMPL_ArenaAlloc
-#endif
-#if !defined(MD_IMPL_ArenaRelease)
-# error Missing implementation for MD_IMPL_ArenaRelease
-#endif
-#if !defined(MD_IMPL_ArenaGetPos)
-# error Missing implementation for MD_IMPL_ArenaGetPos
-#endif
-#if !defined(MD_IMPL_ArenaPush)
-# error Missing implementation for MD_IMPL_ArenaPush
-#endif
-#if !defined(MD_IMPL_ArenaPopTo)
-# error Missing implementation for MD_IMPL_ArenaPopTo
-#endif
-#if !defined(MD_IMPL_ArenaSetAutoAlign)
-# error Missing implementation for MD_IMPL_ArenaSetAutoAlign
-#endif
-#if !defined(MD_IMPL_ArenaHeaderSize)
-# error Missing implementation for MD_IMPL_ArenaHeaderSize
-#endif
-
 MD_FUNCTION_IMPL MD_Arena*
 MD_ArenaAlloc(MD_u64 cap){
     return(MD_IMPL_ArenaAlloc(cap));
@@ -429,36 +480,14 @@ MD_ArenaEndTemp(MD_ArenaTemp temp){
     MD_IMPL_ArenaPopTo(temp.arena, temp.pos);
 }
 
-//~ Thread Context Functions
-
-MD_THREAD_LOCAL MD_ThreadContext *md_thread_ctx;
-
-MD_FUNCTION_IMPL void
-MD_ThreadInit(MD_ThreadContext *tctx_mem){
-    md_thread_ctx = tctx_mem;
-    for (MD_u32 i = 0; i < MD_ArrayCount(md_thread_ctx->scratch_pool); i += 1){
-        tctx_mem->scratch_pool[i] = MD_ArenaAlloc(MD_SCRATCH_SIZE);
-    }
-}
+//~ Arena Scratch Pool
 
 MD_FUNCTION_IMPL MD_ArenaTemp
-MD_GetScratch(MD_Arena **conflicts, MD_u32 count){
+MD_GetScratch(MD_Arena **conflicts, MD_u64 count){
+    MD_Arena *arena = MD_IMPL_GetScratch(conflicts, count);
     MD_ArenaTemp result = MD_ZERO_STRUCT;
-    MD_ThreadContext *tctx = md_thread_ctx;
-    MD_Arena **arena_ptr = tctx->scratch_pool;
-    for (MD_u32 i = 0; i < MD_ArrayCount(tctx->scratch_pool); i += 1, arena_ptr += 1){
-        MD_b32 has_conflict = 0;
-        MD_Arena **conflict_ptr = conflicts;
-        for (MD_u32 j = 0; j < count; j += 1, conflict_ptr += 1){
-            if (*arena_ptr == *conflict_ptr){
-                has_conflict = 1;
-                break;
-            }
-        }
-        if (!has_conflict){
-            result = MD_ArenaBeginTemp(*arena_ptr);
-            break;
-        }
+    if (arena != 0){
+        result = MD_ArenaBeginTemp(arena);
     }
     return(result);
 }
diff --git a/source/md.h b/source/md.h
index 8d9c925..758b040 100644
--- a/source/md.h
+++ b/source/md.h
@@ -7,7 +7,7 @@
 
 /* NOTE(allen): Notes on overrides/macro options:
 **
-** Individual Overridables:
+** Overridable :
 **  "file iteration" ** OPTIONAL
 **   #define MD_IMPL_FileIterIncrement
 **     (MD_Arena*, MD_FileIter*, MD_String8, MD_FileInfo* out) -> MD_b32
@@ -28,14 +28,18 @@
 **   #define MD_IMPL_ArenaSetAutoAlign  (MD_IMPL_Arena*, MD_u64) -> void
 **   #define MD_IMPL_ArenaHeaderSize    MD_u64
 **
-**  "constants" ** REQUIRED (defaults to 1 gigabyte)
-**   #define MD_SCRATCH_SIZE            MD_u64
+**  "scratch" ** REQUIRED (default implementation available)
+**   #define MD_IMPL_GetScratch         (MD_IMPL_Arena**, MD_u64) -> MD_IMPL_Arena*
+**  "scratch constants" ** OPTIONAL (required for default scratch)
+**   #define MD_IMPL_ScratchSize        MD_u64 / default 1 gigabyte
+**   #define MD_IMPL_ScratchCount       MD_u64 / default 2
 **
 ** Default Implementation Controls
 **  These controls default to '1' i.e. 'enabled'
 **   #define MD_DEFAULT_FILE_ITER -> construct "file iteration" from OS headers
 **   #define MD_DEFAULT_MEMORY    -> construct "low level memory" from OS headers
 **   #define MD_DEFAULT_ARENA     -> construct "arena" from "low level memory"
+**   #define MD_DEFAULT_SCRATCH   -> construct "scratch" from "arena"
 **
 */
 
@@ -49,8 +53,8 @@
 #if !defined(MD_DEFAULT_ARENA)
 # define MD_DEFAULT_ARENA 1
 #endif
-#if !defined(MD_SCRATCH_SIZE)
-# define MD_SCRATCH_SIZE (1 << 30)
+#if !defined(MD_DEFAULT_SCRATCH)
+# define MD_DEFAULT_SCRATCH 1
 #endif
 
 
@@ -338,14 +342,6 @@ struct MD_ArenaTemp{
     MD_u64 pos;
 };
 
-//~ Thread Context
-
-// TODO(allen): overrides for get scratch
-typedef struct MD_ThreadContext MD_ThreadContext;
-struct MD_ThreadContext{
-    MD_Arena *scratch_pool[2];
-};
-
 //~ Basic Unicode string types.
 
 typedef struct MD_String8 MD_String8;
@@ -766,10 +762,9 @@ MD_FUNCTION void         MD_ArenaClear(MD_Arena *arena);
 MD_FUNCTION MD_ArenaTemp MD_ArenaBeginTemp(MD_Arena *arena);
 MD_FUNCTION void         MD_ArenaEndTemp(MD_ArenaTemp temp);
 
-//~ Thread Context Functions
+//~ Arena Scratch Pool
 
-MD_FUNCTION void         MD_ThreadInit(MD_ThreadContext *tctx_mem);
-MD_FUNCTION MD_ArenaTemp MD_GetScratch(MD_Arena **conflicts, MD_u32 count);
+MD_FUNCTION MD_ArenaTemp MD_GetScratch(MD_Arena **conflicts, MD_u64 count);
 
 #define MD_ReleaseScratch(scratch) MD_ArenaEndTemp(scratch)
 
diff --git a/tests/cpp_build_test.cpp b/tests/cpp_build_test.cpp
index 1fa785b..78c3583 100644
--- a/tests/cpp_build_test.cpp
+++ b/tests/cpp_build_test.cpp
@@ -5,9 +5,6 @@ static MD_Arena *arena = 0;
 
 int main(void)
 {
-    MD_ThreadContext tctx;
-    MD_ThreadInit(&tctx);
-    
     arena = MD_ArenaAlloc(1ull << 40);
     
     printf("%d\n", MD_CPP_VERSION);
diff --git a/tests/sanity_tests.c b/tests/sanity_tests.c
index 188fc4a..40b07f1 100644
--- a/tests/sanity_tests.c
+++ b/tests/sanity_tests.c
@@ -120,9 +120,6 @@ TokenMatch(MD_Token token, MD_String8 string, MD_TokenKind kind)
 
 int main(void)
 {
-    MD_ThreadContext tctx;
-    MD_ThreadInit(&tctx);
-    
     arena = MD_ArenaAlloc(1ull << 40);
     
     Test("Lexer")
diff --git a/tests/unicode_test.c b/tests/unicode_test.c
index 4886b09..04a7ec9 100644
--- a/tests/unicode_test.c
+++ b/tests/unicode_test.c
@@ -16,9 +16,6 @@ void run_test_on_string(MD_String8 string)
 
 int main(void)
 {
-    MD_ThreadContext tctx;
-    MD_ThreadInit(&tctx);
-    
     arena = MD_ArenaAlloc(1ull << 40);
     
     // TODO(allen): throw more at this.