diff --git a/inc/os_win/threads_types.h b/inc/os_win/threads_types.h
index 8ecc018..1173355 100644
--- a/inc/os_win/threads_types.h
+++ b/inc/os_win/threads_types.h
@@ -4,18 +4,18 @@
 
 #pragma once
 
-typedef struct cnd_t {
-    int idk_yet;
-} cnd_t;
-
 typedef struct thrd_t {
     void *handle;
 } thrd_t;
 
 typedef struct tss_t {
-    int idk_yet;
+    unsigned tls_index;
 } tss_t;
 
+typedef struct cnd_t {
+    int idk_yet;
+} cnd_t;
+
 typedef struct mtx_t {
     int type;
     // Done to handle recursive mutexes
diff --git a/src/os_win/thread.c b/src/os_win/thread.c
index 19021c9..810254c 100644
--- a/src/os_win/thread.c
+++ b/src/os_win/thread.c
@@ -1,4 +1,50 @@
 
+// Note(bumbread):
+// https://gist.github.com/wbenny/6d7fc92e9b5c3194ce56bf8c60d6191d
+
+#pragma comment(linker, "/merge:.CRT=.rdata")
+
+#pragma section(".CRT$XLA", read)
+__declspec(allocate(".CRT$XLA")) const PIMAGE_TLS_CALLBACK __xl_a = NULL;
+
+#pragma section(".CRT$XLZ", read)
+__declspec(allocate(".CRT$XLZ")) const PIMAGE_TLS_CALLBACK __xl_z = NULL;
+
+#pragma section(".CRT$XLM", read)
+__declspec(allocate(".CRT$XLM")) extern const PIMAGE_TLS_CALLBACK TlsCallbackArray;
+
+char _tls_start = 0;
+char _tls_end = 0;
+unsigned int _tls_index = 0;
+
+const IMAGE_TLS_DIRECTORY _tls_used = {
+  (ULONG_PTR)&_tls_start,
+  (ULONG_PTR)&_tls_end,
+  (ULONG_PTR)&_tls_index,
+  (ULONG_PTR)(&__xl_a + 1),
+};
+
+static void _thread_cleanup();
+
+VOID NTAPI _tls_callback(
+  PVOID DllHandle,
+  DWORD Reason,
+  PVOID Reserved
+  )
+{
+  switch(Reason) {
+      case DLL_THREAD_ATTACH: break;
+      case DLL_THREAD_DETACH: {
+          _thread_cleanup();
+      } break;
+      case DLL_PROCESS_ATTACH: break;
+      case DLL_PROCESS_DETACH: break;
+  }
+  // __debugbreak();
+}
+
+const PIMAGE_TLS_CALLBACK TlsCallbackArray = { &_tls_callback };
+
 // NOTE: debug mutexes will follow the recursive logic but error if they
 // actually recurse, this is slower than doing plain logic but it helps
 // debug weird mutex errors.
@@ -7,8 +53,6 @@
 //   https://preshing.com/20120305/implementing-a-recursive-mutex/
 //   https://preshing.com/20120226/roll-your-own-lightweight-mutex/
 
-DWORD _tls_index = 0;
-
 typedef struct UserClosure {
     thrd_start_t func;
     void* arg;
@@ -17,8 +61,6 @@ typedef struct UserClosure {
 static DWORD _thread_call_user(void* arg) {
     UserClosure info = *((UserClosure*) arg);
     int result = info.func(info.arg);
-
-    // TODO(NeGate): setup TSS dtors here
     return (DWORD) result;
 }
 
@@ -78,11 +120,68 @@ void thrd_yield(void) {
 }
 
 _Noreturn void thrd_exit(int res) {
-    // TODO(NeGate): setup TSS dtors here
+    _thread_cleanup();
     ExitThread((DWORD)res);
     __builtin_unreachable();
 }
 
+// TSS functions
+
+#define TSS_KEYS_MAX 1088
+
+static tss_dtor_t _tss_dtors[TSS_KEYS_MAX];
+
+static void _thread_cleanup() {
+    for(int i = 0; i != TSS_DTOR_ITERATIONS; ++i) {
+        for(unsigned k = 0; k != TSS_KEYS_MAX; ++k) {
+            void *data = TlsGetValue(k);
+            if(data != NULL) {
+                TlsSetValue(k, NULL);
+                if(_tss_dtors[k]) {
+                    _tss_dtors[k](data);
+                }
+            }
+        }
+    }
+}
+
+int tss_create(tss_t *key, tss_dtor_t dtor) {
+    DWORD tls_index = TlsAlloc();
+    if(tls_index == TLS_OUT_OF_INDEXES) {
+        return thrd_error;
+    }
+    key->tls_index = tls_index;
+    if(tls_index >= TSS_KEYS_MAX) {
+        __debugbreak();
+        TlsFree(tls_index);
+        return thrd_error;
+    }
+    _tss_dtors[tls_index] = dtor;
+    return thrd_success;
+}
+
+void tss_delete(tss_t key) {
+    _tss_dtors[key.tls_index] = NULL;
+    TlsFree(key.tls_index);
+}
+
+void *tss_get(tss_t key) {
+    void *data = TlsGetValue(key.tls_index);
+    if(data == NULL && GetLastError() != ERROR_SUCCESS) {
+        return NULL;
+    }
+    return data;
+}
+
+int tss_set(tss_t key, void *val) {
+   if(!TlsSetValue(key.tls_index, val)) {
+       return thrd_error;
+   }
+   return thrd_success;
+}
+
+// Mutex functions
+
 void mtx_destroy(mtx_t *mtx) {
     CloseHandle(mtx->semaphore);
 }
diff --git a/test.bat b/test.bat
new file mode 100644
index 0000000..807e319
--- /dev/null
+++ b/test.bat
@@ -0,0 +1,2 @@
+
+clang -g %1 -I inc utf8.obj -nostdlib -mfma -lciabatta.lib
diff --git a/test/test_threads.c b/test/test_threads.c
index 41df77d..ebbb723 100644
--- a/test/test_threads.c
+++ b/test/test_threads.c
@@ -2,29 +2,33 @@
 #include <threads.h>
 #include <stdatomic.h>
 
-atomic_int acnt;
-int cnt;
+_Thread_local int counter;
+tss_t key;
 
-int f(void* thr_data)
-{
+int f(void* thr_data) {
+    tss_set(key, "Thread 2 finished");
     for(int n = 0; n < 5; ++n)
-        puts("b");
+        counter++;
+    puts(tss_get(key));
     return 0;
 }
 
 int main(void)
 {
-    thrd_t thread;
-    int status = thrd_create(&thread, f, NULL);
-    if(status == thrd_error) {
-        puts("Failed creating threads");
-    }
-    for(int n = 0; n < 5; ++n) {
-        puts("a");
-    }
-    int res;
-    if(thrd_join(thread, &res) == thrd_error) {
-        puts("Failed waiting on thread");
-    }
-    puts("Finished");
+    tss_create(&key, NULL);
+    // thrd_t thread;
+    // int status = thrd_create(&thread, f, NULL);
+    // if(status == thrd_error) {
+    //     puts("Failed creating threads");
+    // }
+    // for(int n = 0; n < 10; ++n) {
+    //     counter++;
+    // }
+    tss_set(key, "Thread 1 finished");
+    // int res;
+    // if(thrd_join(thread, &res) == thrd_error) {
+    //     puts("Failed waiting on thread");
+    // }
+    puts(tss_get(key));
+    tss_delete(key);
 }