diff --git a/docs/changelog.md b/docs/changelog.md
index 597260b12..c15e481d3 100644
--- a/docs/changelog.md
+++ b/docs/changelog.md
@@ -41,6 +41,8 @@ Older changelogs:
   [#967](https://github.com/ADOdb/ADOdb/issues/967)
 - pgsql: Fix PHP 8.1 deprecated warning
   [#956](https://github.com/ADOdb/ADOdb/issues/956)
+- pgsql: avoid Insert_ID() failing when lastval() is not set
+  [#978](https://github.com/ADOdb/ADOdb/issues/978)
 
 
 ## [5.22.5] - 2023-04-03
diff --git a/drivers/adodb-postgres8.inc.php b/drivers/adodb-postgres8.inc.php
index 911ec178c..58df47c63 100644
--- a/drivers/adodb-postgres8.inc.php
+++ b/drivers/adodb-postgres8.inc.php
@@ -45,13 +45,19 @@ class ADODB_postgres8 extends ADODB_postgres7
 	 * @return int last inserted ID for given table/column, or the most recently
 	 *             returned one if $table or $column are empty
 	 */
-	protected function _insertID( $table = '', $column = '' ){
-		$sql = 'SELECT ';
-		$sql .= empty($table) || empty($column) ? 'lastval()' : "currval(pg_get_serial_sequence('$table', '$column'))";
+	protected function _insertID( $table = '', $column = '' )
+	{
+		global $ADODB_GETONE_EOF;
+
+		$sql = empty($table) || empty($column)
+			? 'SELECT lastval()'
+			: "SELECT currval(pg_get_serial_sequence('$table', '$column'))";
+
+		// Squelch "ERROR:  lastval is not yet defined in this session" (see #978)
 		$result = @$this->GetOne($sql);
-		if( $result === false || $result == $ADODB_GETONE_EOF ){
-			if( $this->debug ){
-				ADOConnection::outp(__FUNCTION__ . "() failed : "  . $this->errorMsg());
+		if ($result === false || $result == $ADODB_GETONE_EOF) {
+			if ($this->debug) {
+				ADOConnection::outp(__FUNCTION__ . "() failed : " . $this->errorMsg());
 			}
 			return false;
 		}