diff --git a/NEWS b/NEWS
index 366cb537462..02a2ba73744 100644
--- a/NEWS
+++ b/NEWS
@@ -2,4 +2,7 @@ PHP                                                                        NEWS
 |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 ?? ??? ????, PHP 8.2.0alpha1
 
+- Core:
+  . Fixed bug #81380 (Observer may not be initialized properly). (krakjoe)
+
 <<< NOTE: Insert NEWS from last stable release here prior to actual release! >>>
diff --git a/Zend/zend_observer.c b/Zend/zend_observer.c
index 84a36f6db01..35958aeac5a 100644
--- a/Zend/zend_observer.c
+++ b/Zend/zend_observer.c
@@ -44,11 +44,11 @@ zend_llist zend_observer_fiber_init;
 zend_llist zend_observer_fiber_switch;
 zend_llist zend_observer_fiber_destroy;
 
-int zend_observer_fcall_op_array_extension = -1;
+int zend_observer_fcall_op_array_extension;
 
-ZEND_TLS zend_arena *fcall_handlers_arena = NULL;
-ZEND_TLS zend_execute_data *first_observed_frame = NULL;
-ZEND_TLS zend_execute_data *current_observed_frame = NULL;
+ZEND_TLS zend_arena *fcall_handlers_arena;
+ZEND_TLS zend_execute_data *first_observed_frame;
+ZEND_TLS zend_execute_data *current_observed_frame;
 
 // Call during minit/startup ONLY
 ZEND_API void zend_observer_fcall_register(zend_observer_fcall_init init) {
@@ -78,12 +78,18 @@ ZEND_API void zend_observer_startup(void) {
 	zend_llist_init(&zend_observer_fiber_init, sizeof(zend_observer_fiber_init_handler), NULL, 1);
 	zend_llist_init(&zend_observer_fiber_switch, sizeof(zend_observer_fiber_switch_handler), NULL, 1);
 	zend_llist_init(&zend_observer_fiber_destroy, sizeof(zend_observer_fiber_destroy_handler), NULL, 1);
+
+	zend_observer_fcall_op_array_extension = -1;
 }
 
 ZEND_API void zend_observer_activate(void) {
 	if (ZEND_OBSERVER_ENABLED) {
 		fcall_handlers_arena = zend_arena_create(4096);
+	} else {
+		fcall_handlers_arena = NULL;
 	}
+	first_observed_frame = NULL;
+	current_observed_frame = NULL;
 }
 
 ZEND_API void zend_observer_deactivate(void) {