diff --git a/pageserver/src/basebackup.rs b/pageserver/src/basebackup.rs
index 740f48acd0..b6460d3f8e 100644
--- a/pageserver/src/basebackup.rs
+++ b/pageserver/src/basebackup.rs
@@ -322,24 +322,21 @@ impl<'a> Basebackup<'a> {
         pg_control.checkPointCopy = checkpoint;
         pg_control.state = pg_constants::DB_SHUTDOWNED;
 
-        // Postgres doesn't recognize the zenith.signal file and doesn't need it.
-        if !self.full_backup {
-            // add zenith.signal file
-            let mut zenith_signal = String::new();
-            if self.prev_record_lsn == Lsn(0) {
-                if self.lsn == self.timeline.get_ancestor_lsn() {
-                    write!(zenith_signal, "PREV LSN: none")?;
-                } else {
-                    write!(zenith_signal, "PREV LSN: invalid")?;
-                }
+        // add zenith.signal file
+        let mut zenith_signal = String::new();
+        if self.prev_record_lsn == Lsn(0) {
+            if self.lsn == self.timeline.get_ancestor_lsn() {
+                write!(zenith_signal, "PREV LSN: none")?;
             } else {
-                write!(zenith_signal, "PREV LSN: {}", self.prev_record_lsn)?;
+                write!(zenith_signal, "PREV LSN: invalid")?;
             }
-            self.ar.append(
-                &new_tar_header("zenith.signal", zenith_signal.len() as u64)?,
-                zenith_signal.as_bytes(),
-            )?;
+        } else {
+            write!(zenith_signal, "PREV LSN: {}", self.prev_record_lsn)?;
         }
+        self.ar.append(
+            &new_tar_header("zenith.signal", zenith_signal.len() as u64)?,
+            zenith_signal.as_bytes(),
+        )?;
 
         //send pg_control
         let pg_control_bytes = pg_control.encode();
diff --git a/test_runner/batch_others/test_fullbackup.py b/test_runner/batch_others/test_fullbackup.py
index f3090278dd..4f4973732d 100644
--- a/test_runner/batch_others/test_fullbackup.py
+++ b/test_runner/batch_others/test_fullbackup.py
@@ -69,5 +69,6 @@ def test_fullbackup(zenith_env_builder: ZenithEnvBuilder,
             f"port={port}",
         ])
         vanilla_pg.start()
-        num_rows_found = vanilla_pg.safe_psql('select count(*) from tbl;', user="cloud_admin")[0][0]
+        num_rows_found = vanilla_pg.safe_psql('select count(*) from tbl;',
+                                              username="zenith_admin")[0][0]
         assert num_rows == num_rows_found