diff --git a/Misc/NEWS.d/next/Build/2021-06-19-18-04-47.bpo-32307.V1wzBY.rst b/Misc/NEWS.d/next/Build/2021-06-19-18-04-47.bpo-32307.V1wzBY.rst
new file mode 100644
index 00000000000000..d767051b9f8a0a
--- /dev/null
+++ b/Misc/NEWS.d/next/Build/2021-06-19-18-04-47.bpo-32307.V1wzBY.rst
@@ -0,0 +1,4 @@
+Force a default thread stack size value for all platforms instead of
+assuming that they all have enough for Python threads. This makes it so too
+many recursions are caught by the interpreter instead of stack overflowing
+on musl libc.
diff --git a/Python/thread_pthread.h b/Python/thread_pthread.h
index e660bca8406860..bec8e9b20f8c77 100644
--- a/Python/thread_pthread.h
+++ b/Python/thread_pthread.h
@@ -40,7 +40,9 @@
    be conditional on _POSIX_THREAD_ATTR_STACKSIZE being defined. */
 #ifdef _POSIX_THREAD_ATTR_STACKSIZE
 #ifndef THREAD_STACK_SIZE
-#define THREAD_STACK_SIZE       0       /* use default stack size */
+/* -1 means THREAD_STACK_SIZE hasn't been given a proper value yet.
+   -DTHREAD_STACK_SIZE=0 in CFLAGS will force the platform's default instead. */
+#define THREAD_STACK_SIZE       -1
 #endif
 
 /* The default stack size for new threads on BSD is small enough that
@@ -54,28 +56,30 @@
  * as it also depends on the other configure options like chosen sanitizer
  * runtimes.
  */
-#if defined(__FreeBSD__) && defined(THREAD_STACK_SIZE) && THREAD_STACK_SIZE == 0
+#if defined(__FreeBSD__) && THREAD_STACK_SIZE == -1
 #undef  THREAD_STACK_SIZE
 #define THREAD_STACK_SIZE       0x400000
 #endif
-#if defined(_AIX) && defined(THREAD_STACK_SIZE) && THREAD_STACK_SIZE == 0
-#undef  THREAD_STACK_SIZE
-#define THREAD_STACK_SIZE       0x200000
-#endif
 /* bpo-38852: test_threading.test_recursion_limit() checks that 1000 recursive
    Python calls (default recursion limit) doesn't crash, but raise a regular
    RecursionError exception. In debug mode, Python function calls allocates
    more memory on the stack, so use a stack of 8 MiB. */
-#if defined(__ANDROID__) && defined(THREAD_STACK_SIZE) && THREAD_STACK_SIZE == 0
+#if defined(__ANDROID__) && THREAD_STACK_SIZE == -1
 #   ifdef Py_DEBUG
 #   undef  THREAD_STACK_SIZE
 #   define THREAD_STACK_SIZE    0x800000
 #   endif
 #endif
-#if defined(__VXWORKS__) && defined(THREAD_STACK_SIZE) && THREAD_STACK_SIZE == 0
+#if defined(__VXWORKS__) && THREAD_STACK_SIZE == -1
 #undef  THREAD_STACK_SIZE
 #define THREAD_STACK_SIZE       0x100000
 #endif
+#if THREAD_STACK_SIZE == -1
+#undef  THREAD_STACK_SIZE
+/* This is big enough for most platforms without being wasteful. */
+#define THREAD_STACK_SIZE       0x200000
+#endif
+
 /* for safety, ensure a viable minimum stacksize */
 #define THREAD_STACK_MIN        0x8000  /* 32 KiB */
 #else  /* !_POSIX_THREAD_ATTR_STACKSIZE */