diff --git a/Makefile.in b/Makefile.in
index c7bab1a2..c161bccf 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -367,7 +367,8 @@ TESTS_ANALYZE := $(srcroot)test/analyze/prof_bias.c \
 TESTS_STRESS := $(srcroot)test/stress/fill_flush.c \
 	$(srcroot)test/stress/large_microbench.c \
 	$(srcroot)test/stress/mallctl.c \
-	$(srcroot)test/stress/microbench.c
+	$(srcroot)test/stress/microbench.c \
+	$(srcroot)test/stress/tsd_reentrant.c
 ifeq (@enable_cxx@, 1)
 TESTS_STRESS_CPP := $(srcroot)test/stress/cpp/microbench.cpp
 else
diff --git a/include/jemalloc/internal/test_hooks.h b/include/jemalloc/internal/test_hooks.h
index 1b56c717..a4c9d6c0 100644
--- a/include/jemalloc/internal/test_hooks.h
+++ b/include/jemalloc/internal/test_hooks.h
@@ -4,6 +4,7 @@
 extern JEMALLOC_EXPORT void (*test_hooks_arena_new_hook)(void);
 extern JEMALLOC_EXPORT void (*test_hooks_libc_hook)(void);
 extern JEMALLOC_EXPORT void (*test_hooks_safety_check_abort)(const char *);
+extern JEMALLOC_EXPORT void (*test_hooks_tsd_bootstrap_hook)(void);
 
 #if defined(JEMALLOC_JET) || defined(JEMALLOC_UNIT_TEST)
 #	define JEMALLOC_TEST_HOOK(fn, hook)                                   \
diff --git a/src/tcache.c b/src/tcache.c
index 5f6b8239..87a44522 100644
--- a/src/tcache.c
+++ b/src/tcache.c
@@ -1051,6 +1051,9 @@ tsd_tcache_enabled_data_init(tsd_t *tsd) {
 	 */
 	tcache_default_settings_init(tsd_tcache_slowp_get(tsd));
 	tsd_slow_update(tsd);
+	if (test_hooks_tsd_bootstrap_hook != NULL) {
+		test_hooks_tsd_bootstrap_hook();
+	}
 
 	if (opt_tcache) {
 		/* Trigger tcache init. */
diff --git a/src/test_hooks.c b/src/test_hooks.c
index 0f4c4cf7..3fc8534e 100644
--- a/src/test_hooks.c
+++ b/src/test_hooks.c
@@ -13,3 +13,6 @@ void (*test_hooks_libc_hook)(void) = NULL;
 
 JEMALLOC_EXPORT
 void (*test_hooks_safety_check_abort)(const char *) = NULL;
+
+JEMALLOC_EXPORT
+void (*test_hooks_tsd_bootstrap_hook)(void) = NULL;
diff --git a/test/stress/tsd_reentrant.c b/test/stress/tsd_reentrant.c
new file mode 100644
index 00000000..220f1c3e
--- /dev/null
+++ b/test/stress/tsd_reentrant.c
@@ -0,0 +1,140 @@
+#include "test/jemalloc_test.h"
+
+#ifndef _WIN32
+#include <signal.h>
+#include <unistd.h>
+#endif
+
+#ifndef _WIN32
+
+extern void (*je_test_hooks_tsd_bootstrap_hook)(void);
+
+static atomic_zu_t handler_allocs;
+
+static atomic_b_t crash_reported;
+static bool hook_ran;
+static volatile sig_atomic_t in_reentrant_signal_alloc;
+
+static void *volatile signal_alloc;
+
+static void
+on_crash(int signo) {
+#define WRITE_LITERAL(s) (void)write(STDERR_FILENO, s, sizeof(s) - 1)
+	if (atomic_exchange_b(&crash_reported, true, ATOMIC_RELAXED)) {
+		_exit(128 + signo);
+	}
+
+	WRITE_LITERAL("\n*** tsd_reentrant reproduced allocator crash ***\n");
+	if (signo == SIGSEGV) {
+		WRITE_LITERAL("signal: SIGSEGV\n");
+	} else if (signo == SIGBUS) {
+		WRITE_LITERAL("signal: SIGBUS\n");
+	}
+	WRITE_LITERAL("inside SIGUSR1 handler malloc: ");
+	if (in_reentrant_signal_alloc) {
+		WRITE_LITERAL("yes\n");
+	} else {
+		WRITE_LITERAL("no\n");
+	}
+	WRITE_LITERAL("This matches recursive allocation during TSD/tcache "
+	    "bootstrap.\n");
+#undef WRITE_LITERAL
+
+	_exit(128 + signo);
+}
+
+static void
+on_signal(int signo) {
+	(void)signo;
+	in_reentrant_signal_alloc = 1;
+
+	/*
+	 * This intentionally models asynchronous interruption that allocates.
+	 * jemalloc does not promise that arbitrary signal-handler allocation is
+	 * safe, but the allocator should keep its own bootstrap state
+	 * internally consistent if such reentrancy occurs.
+	 */
+	void *p = malloc(16);
+	if (p != NULL) {
+		signal_alloc = p;
+		atomic_load_add_store_zu(&handler_allocs, 1);
+	}
+	in_reentrant_signal_alloc = 0;
+}
+
+static void
+tsd_bootstrap_signal_hook(void) {
+	hook_ran = true;
+	je_test_hooks_tsd_bootstrap_hook = NULL;
+	/*
+	 * The hook only selects the bootstrap window.  The recursive allocation
+	 * still enters through the process signal path and public malloc().
+	 */
+	raise(SIGUSR1);
+}
+
+static void *
+worker_start(void *arg) {
+	(void)arg;
+	void *p = malloc(16);
+	expect_ptr_not_null(p, "Unexpected malloc() failure");
+	if (p != NULL) {
+		memset(p, 0xa5, 16);
+		free(p);
+	}
+
+	je_test_hooks_tsd_bootstrap_hook = NULL;
+
+	return NULL;
+}
+
+static void
+init_signal_handler(void) {
+	struct sigaction sa;
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_handler = on_signal;
+	sa.sa_flags = SA_RESTART;
+	sigemptyset(&sa.sa_mask);
+	expect_d_eq(sigaction(SIGUSR1, &sa, NULL), 0,
+	    "Unexpected sigaction() failure");
+
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_handler = on_crash;
+	sigemptyset(&sa.sa_mask);
+	expect_d_eq(sigaction(SIGSEGV, &sa, NULL), 0,
+	    "Unexpected sigaction() failure");
+	expect_d_eq(sigaction(SIGBUS, &sa, NULL), 0,
+	    "Unexpected sigaction() failure");
+}
+
+TEST_BEGIN(test_tsd_bootstrap_signal_reentrant) {
+	thd_t worker;
+
+	init_signal_handler();
+
+	atomic_store_b(&crash_reported, false, ATOMIC_RELEASE);
+	atomic_store_zu(&handler_allocs, 0, ATOMIC_RELEASE);
+	hook_ran = false;
+
+	je_test_hooks_tsd_bootstrap_hook = tsd_bootstrap_signal_hook;
+	thd_create(&worker, worker_start, NULL);
+	thd_join(worker, NULL);
+	je_test_hooks_tsd_bootstrap_hook = NULL;
+
+	expect_true(hook_ran, "TSD bootstrap hook should have executed");
+	expect_zu_eq(atomic_load_zu(&handler_allocs, ATOMIC_ACQUIRE), 1,
+	    "Signal handler should have allocated");
+}
+TEST_END
+
+#endif
+
+int
+main(void) {
+#ifdef _WIN32
+	test_skip("Signals are unavailable");
+	return test_status_skip;
+#else
+	return test_no_reentrancy(test_tsd_bootstrap_signal_reentrant);
+#endif
+}