diff --git a/src/spock_apply.c b/src/spock_apply.c
index b93b3db9..ae308ab7 100644
--- a/src/spock_apply.c
+++ b/src/spock_apply.c
@@ -1226,6 +1226,13 @@ handle_insert(StringInfo s)
 		 */
 		xact_had_exception = true;
 		exception_command_counter++;
+
+		/*
+		 * Clear the local tuple pointer if it was left over from a
+		 * previous operation.
+		 */
+		exception_log_ptr[my_exception_log_index].local_tuple = NULL;
+
 		log_insert_exception(true, "Spock can't find relation", NULL,
 							 NULL, NULL, "INSERT");
 		end_replication_step();
@@ -3259,6 +3266,12 @@ static void
 execute_sql_command_error_cb(void *arg)
 {
 	errcontext("during execution of queued SQL statement: %s", (char *) arg);
+	/*
+	 * The errcontext above already includes the SQL statement, so clear
+	 * debug_query_string to prevent it from appearing a second time in
+	 * the LOG output.
+	 */
+	debug_query_string = NULL;
 }
 
 /*
@@ -3779,6 +3792,13 @@ spock_apply_main(Datum main_arg)
 	Assert(MySpockWorker->worker_type == SPOCK_WORKER_APPLY);
 	MyApplyWorker = &MySpockWorker->worker.apply;
 
+	/*
+	 * The apply worker is not a regular backend and has no client query
+	 * string. Initialize debug_query_string to NULL so that LOG reports
+	 * do not print arbitrary memory contents.
+	 */
+	debug_query_string = NULL;
+
 	/* Setup synchronous commit according to the user's wishes */
 	SetConfigOption("synchronous_commit",
 					spock_synchronous_commit ? "local" : "off",