diff --git a/include/jemalloc/internal/hook.h b/include/jemalloc/internal/hook.h
index fc61e9bd..678c6018 100644
--- a/include/jemalloc/internal/hook.h
+++ b/include/jemalloc/internal/hook.h
@@ -103,6 +103,7 @@ struct hooks_s {
 	hook_alloc alloc_hook;
 	hook_dalloc dalloc_hook;
 	hook_expand expand_hook;
+	void *extra;
 };
 
 /*
@@ -142,7 +143,7 @@ struct hook_ralloc_args_s {
  */
 bool hook_boot();
 
-void *hook_install(tsdn_t *tsdn, hooks_t *hooks, void *extra);
+void *hook_install(tsdn_t *tsdn, hooks_t *hooks);
 /* Uninstalls the hook with the handle previously returned from hook_install. */
 void hook_remove(tsdn_t *tsdn, void *opaque);
 
diff --git a/src/hook.c b/src/hook.c
index 5c6818ff..564c2a0c 100644
--- a/src/hook.c
+++ b/src/hook.c
@@ -9,7 +9,6 @@
 typedef struct hooks_internal_s hooks_internal_t;
 struct hooks_internal_s {
 	hooks_t hooks;
-	void *extra;
 	bool in_use;
 };
 
@@ -27,7 +26,7 @@ hook_boot() {
 }
 
 static void *
-hook_install_locked(hooks_t *to_install, void *extra) {
+hook_install_locked(hooks_t *to_install) {
 	hooks_internal_t hooks_internal;
 	for (int i = 0; i < HOOKS_MAX; i++) {
 		bool success = seq_try_load_hooks(&hooks_internal, &hooks[i]);
@@ -35,7 +34,6 @@ hook_install_locked(hooks_t *to_install, void *extra) {
 		assert(success);
 		if (!hooks_internal.in_use) {
 			hooks_internal.hooks = *to_install;
-			hooks_internal.extra = extra;
 			hooks_internal.in_use = true;
 			seq_store_hooks(&hooks[i], &hooks_internal);
 			atomic_store_u(&nhooks,
@@ -48,9 +46,9 @@ hook_install_locked(hooks_t *to_install, void *extra) {
 }
 
 void *
-hook_install(tsdn_t *tsdn, hooks_t *to_install, void *extra) {
+hook_install(tsdn_t *tsdn, hooks_t *to_install) {
 	malloc_mutex_lock(tsdn, &hooks_mu);
-	void *ret = hook_install_locked(to_install, extra);
+	void *ret = hook_install_locked(to_install);
 	if (ret != NULL) {
 		tsd_global_slow_inc(tsdn);
 	}
@@ -112,7 +110,7 @@ hook_invoke_alloc(hook_alloc_t type, void *result, uintptr_t result_raw,
 	FOR_EACH_HOOK_BEGIN(&hook)
 		hook_alloc h = hook.hooks.alloc_hook;
 		if (h != NULL) {
-			h(hook.extra, type, result, result_raw, args_raw);
+			h(hook.hooks.extra, type, result, result_raw, args_raw);
 		}
 	FOR_EACH_HOOK_END
 }
@@ -126,7 +124,7 @@ hook_invoke_dalloc(hook_dalloc_t type, void *address, uintptr_t args_raw[3]) {
 	FOR_EACH_HOOK_BEGIN(&hook)
 		hook_dalloc h = hook.hooks.dalloc_hook;
 		if (h != NULL) {
-			h(hook.extra, type, address, args_raw);
+			h(hook.hooks.extra, type, address, args_raw);
 		}
 	FOR_EACH_HOOK_END
 }
@@ -141,7 +139,7 @@ hook_invoke_expand(hook_expand_t type, void *address, size_t old_usize,
 	FOR_EACH_HOOK_BEGIN(&hook)
 		hook_expand h = hook.hooks.expand_hook;
 		if (h != NULL) {
-			h(hook.extra, type, address, old_usize, new_usize,
+			h(hook.hooks.extra, type, address, old_usize, new_usize,
 			    result_raw, args_raw);
 		}
 	FOR_EACH_HOOK_END
diff --git a/test/unit/hook.c b/test/unit/hook.c
index 693cb238..3f85ff10 100644
--- a/test/unit/hook.c
+++ b/test/unit/hook.c
@@ -81,8 +81,9 @@ test_expand_hook(void *extra, hook_expand_t type, void *address,
 TEST_BEGIN(test_hooks_basic) {
 	/* Just verify that the record their arguments correctly. */
 	hooks_t hooks = {
-		&test_alloc_hook, &test_dalloc_hook, &test_expand_hook};
-	void *handle = hook_install(TSDN_NULL, &hooks, (void *)111);
+		&test_alloc_hook, &test_dalloc_hook, &test_expand_hook,
+		(void *)111};
+	void *handle = hook_install(TSDN_NULL, &hooks);
 	uintptr_t args_raw[4] = {10, 20, 30, 40};
 
 	/* Alloc */
@@ -124,15 +125,15 @@ TEST_END
 
 TEST_BEGIN(test_hooks_null) {
 	/* Null hooks should be ignored, not crash. */
-	hooks_t hooks1 = {NULL, NULL, NULL};
-	hooks_t hooks2 = {&test_alloc_hook, NULL, NULL};
-	hooks_t hooks3 = {NULL, &test_dalloc_hook, NULL};
-	hooks_t hooks4 = {NULL, NULL, &test_expand_hook};
+	hooks_t hooks1 = {NULL, NULL, NULL, NULL};
+	hooks_t hooks2 = {&test_alloc_hook, NULL, NULL, NULL};
+	hooks_t hooks3 = {NULL, &test_dalloc_hook, NULL, NULL};
+	hooks_t hooks4 = {NULL, NULL, &test_expand_hook, NULL};
 
-	void *handle1 = hook_install(TSDN_NULL, &hooks1, NULL);
-	void *handle2 = hook_install(TSDN_NULL, &hooks2, NULL);
-	void *handle3 = hook_install(TSDN_NULL, &hooks3, NULL);
-	void *handle4 = hook_install(TSDN_NULL, &hooks4, NULL);
+	void *handle1 = hook_install(TSDN_NULL, &hooks1);
+	void *handle2 = hook_install(TSDN_NULL, &hooks2);
+	void *handle3 = hook_install(TSDN_NULL, &hooks3);
+	void *handle4 = hook_install(TSDN_NULL, &hooks4);
 
 	assert_ptr_ne(handle1, NULL, "Hook installation failed");
 	assert_ptr_ne(handle2, NULL, "Hook installation failed");
@@ -161,8 +162,8 @@ TEST_BEGIN(test_hooks_null) {
 TEST_END
 
 TEST_BEGIN(test_hooks_remove) {
-	hooks_t hooks = {&test_alloc_hook, NULL, NULL};
-	void *handle = hook_install(TSDN_NULL, &hooks, NULL);
+	hooks_t hooks = {&test_alloc_hook, NULL, NULL, NULL};
+	void *handle = hook_install(TSDN_NULL, &hooks);
 	assert_ptr_ne(handle, NULL, "Hook installation failed");
 	call_count = 0;
 	uintptr_t args_raw[4] = {10, 20, 30, 40};
@@ -179,8 +180,8 @@ TEST_END
 
 TEST_BEGIN(test_hooks_alloc_simple) {
 	/* "Simple" in the sense that we're not in a realloc variant. */
-	hooks_t hooks = {&test_alloc_hook, NULL, NULL};
-	void *handle = hook_install(TSDN_NULL, &hooks, (void *)123);
+	hooks_t hooks = {&test_alloc_hook, NULL, NULL, (void *)123};
+	void *handle = hook_install(TSDN_NULL, &hooks);
 	assert_ptr_ne(handle, NULL, "Hook installation failed");
 
 	/* Stop malloc from being optimized away. */
@@ -290,8 +291,8 @@ TEST_END
 
 TEST_BEGIN(test_hooks_dalloc_simple) {
 	/* "Simple" in the sense that we're not in a realloc variant. */
-	hooks_t hooks = {NULL, &test_dalloc_hook, NULL};
-	void *handle = hook_install(TSDN_NULL, &hooks, (void *)123);
+	hooks_t hooks = {NULL, &test_dalloc_hook, NULL, (void *)123};
+	void *handle = hook_install(TSDN_NULL, &hooks);
 	assert_ptr_ne(handle, NULL, "Hook installation failed");
 
 	void *volatile ptr;
@@ -337,8 +338,8 @@ TEST_END
 
 TEST_BEGIN(test_hooks_expand_simple) {
 	/* "Simple" in the sense that we're not in a realloc variant. */
-	hooks_t hooks = {NULL, NULL, &test_expand_hook};
-	void *handle = hook_install(TSDN_NULL, &hooks, (void *)123);
+	hooks_t hooks = {NULL, NULL, &test_expand_hook, (void *)123};
+	void *handle = hook_install(TSDN_NULL, &hooks);
 	assert_ptr_ne(handle, NULL, "Hook installation failed");
 
 	void *volatile ptr;
@@ -365,8 +366,8 @@ TEST_END
 
 TEST_BEGIN(test_hooks_realloc_as_malloc_or_free) {
 	hooks_t hooks = {&test_alloc_hook, &test_dalloc_hook,
-		&test_expand_hook};
-	void *handle = hook_install(TSDN_NULL, &hooks, (void *)123);
+		&test_expand_hook, (void *)123};
+	void *handle = hook_install(TSDN_NULL, &hooks);
 	assert_ptr_ne(handle, NULL, "Hook installation failed");
 
 	void *volatile ptr;
@@ -416,8 +417,8 @@ static void
 do_realloc_test(void *(*ralloc)(void *, size_t, int), int flags,
     int expand_type, int dalloc_type) {
 	hooks_t hooks = {&test_alloc_hook, &test_dalloc_hook,
-		&test_expand_hook};
-	void *handle = hook_install(TSDN_NULL, &hooks, (void *)123);
+		&test_expand_hook, (void *)123};
+	void *handle = hook_install(TSDN_NULL, &hooks);
 	assert_ptr_ne(handle, NULL, "Hook installation failed");
 
 	void *volatile ptr;