diff --git a/src/main/java/org/duckdb/DuckDBAppender.java b/src/main/java/org/duckdb/DuckDBAppender.java
index ac300563b..92448c2de 100644
--- a/src/main/java/org/duckdb/DuckDBAppender.java
+++ b/src/main/java/org/duckdb/DuckDBAppender.java
@@ -985,7 +985,13 @@ private Column nextColumn(Column curCol) {
         if (null == curCol.parent) {
             cols = columns;
         } else {
-            cols = curCol.parent.children;
+            if (DUCKDB_TYPE_UNION == curCol.parent.colType) {
+                curCol = curCol.parent;
+                // recurse up the union
+                return nextColumn(curCol);
+            } else {
+                cols = curCol.parent.children;
+            }
         }
         int nextColIdx = curCol.idx + 1;
         if (nextColIdx < cols.size()) {
@@ -1004,11 +1010,7 @@ private Column nextColumn(Column curCol) {
     private void moveToNextColumn() throws SQLException {
         Column col = currentColumn();
         this.prevColumn = currentColumn;
-        if (unionBegunInvariant()) {
-            this.currentColumn = nextColumn(col.parent);
-        } else {
-            this.currentColumn = nextColumn(col);
-        }
+        this.currentColumn = nextColumn(col);
     }
 
     // checks
@@ -2127,11 +2129,6 @@ private boolean structCompletedInvariant() {
             prevColumn.idx == prevColumn.parent.children.size() - 1;
     }
 
-    private boolean unionBegunInvariant() {
-        return null != currentColumn && null != currentColumn.parent &&
-            currentColumn.parent.colType == DUCKDB_TYPE_UNION;
-    }
-
     private boolean unionCompletedInvariant() {
         return null != prevColumn && null != prevColumn.parent && prevColumn.parent.colType == DUCKDB_TYPE_UNION;
     }
diff --git a/src/test/java/org/duckdb/TestAppenderComposite.java b/src/test/java/org/duckdb/TestAppenderComposite.java
index d063e5f0c..ddcc1053c 100644
--- a/src/test/java/org/duckdb/TestAppenderComposite.java
+++ b/src/test/java/org/duckdb/TestAppenderComposite.java
@@ -480,6 +480,113 @@ public static void test_appender_union_nested() throws Exception {
         }
     }
 
+    public static void test_appender_union_struct() throws Exception {
+        try (DuckDBConnection conn = DriverManager.getConnection(JDBC_URL).unwrap(DuckDBConnection.class);
+             Statement stmt = conn.createStatement()) {
+            stmt.execute("CREATE TABLE tab1 ("
+                         + "col1 INTEGER, "
+                         + "col2 UNION("
+                         + "    u1 STRUCT("
+                         + "        s1 INTEGER, "
+                         + "        s2 INTEGER"
+                         + "        ), "
+                         + "    u2 INTEGER"
+                         + "    )"
+                         + ")");
+
+            try (DuckDBAppender appender = conn.createAppender("tab1")) {
+                appender.beginRow()
+                    .append(42)
+                    .beginUnion("u1")
+                    .beginStruct()
+                    .append(43)
+                    .append(44)
+                    .endStruct()
+                    .endUnion()
+                    .endRow()
+
+                    .beginRow()
+                    .append(45)
+                    .beginUnion("u2")
+                    .append(46)
+                    .endUnion()
+                    .endRow()
+
+                    .beginRow()
+                    .append(47)
+                    .beginUnion("u1")
+                    .appendNull()
+                    .endUnion()
+                    .endRow()
+
+                    .beginRow()
+                    .append(48)
+                    .beginUnion("u2")
+                    .appendNull()
+                    .endUnion()
+                    .endRow()
+
+                    .beginRow()
+                    .append(49)
+                    .appendNull()
+                    .endRow()
+
+                    .beginRow()
+                    .append(50)
+                    .beginUnion("u1")
+                    .beginStruct()
+                    .append(51)
+                    .append(52)
+                    .endStruct()
+                    .endUnion()
+                    .endRow();
+            }
+
+            try (ResultSet rs = stmt.executeQuery("SELECT * FROM tab1 ORDER BY col1")) {
+                {
+                    assertTrue(rs.next());
+                    assertEquals(rs.getInt(1), 42);
+                    DuckDBStruct struct = (DuckDBStruct) rs.getObject(2);
+                    Map<String, Object> map = struct.getMap();
+                    assertEquals(map.size(), 2);
+                    assertEquals(map.get("s1"), 43);
+                    assertEquals(map.get("s2"), 44);
+                }
+
+                assertTrue(rs.next());
+                assertEquals(rs.getInt(1), 45);
+                assertEquals(rs.getInt(2), 46);
+
+                assertTrue(rs.next());
+                assertEquals(rs.getInt(1), 47);
+                assertNull(rs.getObject(2));
+                assertFalse(rs.wasNull());
+
+                assertTrue(rs.next());
+                assertEquals(rs.getInt(1), 48);
+                assertNull(rs.getObject(2));
+                assertFalse(rs.wasNull());
+
+                assertTrue(rs.next());
+                assertEquals(rs.getInt(1), 49);
+                assertNull(rs.getObject(2));
+                assertTrue(rs.wasNull());
+
+                {
+                    assertTrue(rs.next());
+                    assertEquals(rs.getInt(1), 50);
+                    DuckDBStruct struct = (DuckDBStruct) rs.getObject(2);
+                    Map<String, Object> map = struct.getMap();
+                    assertEquals(map.size(), 2);
+                    assertEquals(map.get("s1"), 51);
+                    assertEquals(map.get("s2"), 52);
+                }
+
+                assertFalse(rs.next());
+            }
+        }
+    }
+
     private static void assertFetchedStructEquals(Object dbs, Collection<Object> struct) throws Exception {
         DuckDBStruct dbStruct = (DuckDBStruct) dbs;
         Map<String, Object> map = dbStruct.getMap();