diff --git a/include/spock.h b/include/spock.h
index 891d616b..a0fe5cf6 100644
--- a/include/spock.h
+++ b/include/spock.h
@@ -50,7 +50,7 @@ extern bool spock_include_ddl_repset;
 extern bool allow_ddl_from_functions;
 extern int	restart_delay_default;
 extern int	restart_delay_on_exception;
-extern int	spock_replay_queue_size;	/* Deprecated - no longer used */
+extern int	spock_replay_queue_size;
 extern int	spock_feedback_frequency;
 extern bool check_all_uc_indexes;
 extern bool	spock_enable_quiet_mode;
diff --git a/src/spock.c b/src/spock.c
index 2aa74433..2829eb10 100644
--- a/src/spock.c
+++ b/src/spock.c
@@ -139,7 +139,7 @@ bool		spock_include_ddl_repset = false;
 bool		allow_ddl_from_functions = false;
 int			restart_delay_default;
 int			restart_delay_on_exception;
-int			spock_replay_queue_size;	/* Deprecated - no longer used */
+int			spock_replay_queue_size;
 int			spock_feedback_frequency;
 bool		check_all_uc_indexes = false;
 bool		spock_enable_quiet_mode = false;
@@ -1150,11 +1150,10 @@ _PG_init(void)
 							NULL);
 
 	DefineCustomIntVariable("spock.exception_replay_queue_size",
-							"DEPRECATED: apply-worker replay queue size (no longer used)",
-							"This setting is deprecated and has no effect. "
-							"The replay queue now dynamically allocates memory as needed.",
+							"apply-worker replay queue size for exception",
+							NULL,
 							&spock_replay_queue_size,
-							4,
+							16,
 							0,
 							MAX_KILOBYTES / 1024,
 							PGC_SIGHUP,
diff --git a/src/spock_apply.c b/src/spock_apply.c
index 46d7d96d..f319fb6b 100644
--- a/src/spock_apply.c
+++ b/src/spock_apply.c
@@ -124,6 +124,7 @@ static ApplyReplayEntry * apply_replay_head = NULL;
 static ApplyReplayEntry * apply_replay_tail = NULL;
 static ApplyReplayEntry * apply_replay_next = NULL;
 static int	apply_replay_bytes = 0;
+static bool	apply_replay_overflow = false;
 
 /* Number of tuples inserted after which we switch to multi-insert. */
 #define MIN_MULTI_INSERT_TUPLES 5
@@ -2268,10 +2269,6 @@ handle_sql_or_exception(QueuedMessage *queued_message, bool tx_just_started)
 
 		if (!failed)
 		{
-			/*
-			 * Follow spock.exception_behavior GUC instead of restarting
-			 * worker
-			 */
 			if (exception_behaviour == TRANSDISCARD ||
 				exception_behaviour == SUB_DISABLE)
 				RollbackAndReleaseCurrentSubTransaction();
@@ -2971,24 +2968,33 @@ apply_work(PGconn *streamConn)
 						last_received = end_lsn;
 
 					/*
-					 * Append the entry to the end of the replay queue if we
-					 * read it from the stream. Dynamic allocation means no
-					 * fixed size limit - queue grows as needed. Note:
-					 * spock_replay_queue_size is deprecated and no longer
-					 * checked.
+					 * Append the entry to the end of the replay queue
+					 * if we read it from the stream but check for overflow.
 					 */
 					if (queue_append)
 					{
 						apply_replay_bytes += msg->len;
 
-						if (apply_replay_head == NULL)
+						/*
+						 * spock_replay_queue_size is stored in KB (GUC_UNIT_MB
+						 * converts the user-facing MB value to KB internally),
+						 * so multiply by 1024 to compare against bytes.
+						 */
+						if (apply_replay_bytes < spock_replay_queue_size * 1024)
 						{
-							apply_replay_head = apply_replay_tail = entry;
+							if (apply_replay_head == NULL)
+							{
+								apply_replay_head = apply_replay_tail = entry;
+							}
+							else
+							{
+								apply_replay_tail->next = entry;
+								apply_replay_tail = entry;
+							}
 						}
 						else
 						{
-							apply_replay_tail->next = entry;
-							apply_replay_tail = entry;
+							apply_replay_overflow = true;
 						}
 					}
 
@@ -3009,10 +3015,10 @@ apply_work(PGconn *streamConn)
 
 					replication_handler(msg);
 
-					/*
-					 * Note: No overflow handling needed - dynamic allocation
-					 * used
-					 */
+					if (queue_append && apply_replay_overflow)
+					{
+						apply_replay_entry_free(entry);
+					}
 				}
 				else if (c == 'k')
 				{
@@ -3186,11 +3192,14 @@ apply_work(PGconn *streamConn)
 		}
 
 		/*
-		 * Note: Replay queue overflow handling removed - dynamic allocation
-		 * prevents overflow. We no longer kill and restart apply workers for
-		 * queue overflow. Exception handling now follows
-		 * spock.exception_behavior setting.
+		 * If we ran out of queue space we also need to bail out.
 		 */
+		if (apply_replay_overflow)
+		{
+			elog(LOG, "SPOCK: caught exception after replay queue overrun "
+				 "- forcing apply worker restart");
+			PG_RE_THROW();
+		}
 
 		/*
 		 * Reaching this point means that we are dealing with the first
@@ -3940,6 +3949,7 @@ apply_replay_queue_reset(void)
 	apply_replay_tail = NULL;
 	apply_replay_next = NULL;
 	apply_replay_bytes = 0;
+	apply_replay_overflow = false;
 
 	MemoryContextReset(ApplyReplayContext);
 }