diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/unnest/ASTERIXDB-2844_unnest_syntax/ASTERIXDB-2844_unnest_syntax.1.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/unnest/ASTERIXDB-2844_unnest_syntax/ASTERIXDB-2844_unnest_syntax.1.query.sqlpp
new file mode 100644
index 0000000..110eefd
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/unnest/ASTERIXDB-2844_unnest_syntax/ASTERIXDB-2844_unnest_syntax.1.query.sqlpp
@@ -0,0 +1,23 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+with t as (select r, [r*10,r*10+1] ra from range(1, 2) r)
+select *
+from t unnest t.ra
+order by ra
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/unnest/ASTERIXDB-2844_unnest_syntax/ASTERIXDB-2844_unnest_syntax.1.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/unnest/ASTERIXDB-2844_unnest_syntax/ASTERIXDB-2844_unnest_syntax.1.adm
new file mode 100644
index 0000000..6b71814
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/unnest/ASTERIXDB-2844_unnest_syntax/ASTERIXDB-2844_unnest_syntax.1.adm
@@ -0,0 +1,4 @@
+{ "t": { "r": 1, "ra": [ 10, 11 ] }, "ra": 10 }
+{ "t": { "r": 1, "ra": [ 10, 11 ] }, "ra": 11 }
+{ "t": { "r": 2, "ra": [ 20, 21 ] }, "ra": 20 }
+{ "t": { "r": 2, "ra": [ 20, 21 ] }, "ra": 21 }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/testsuite_sqlpp.xml b/asterixdb/asterix-app/src/test/resources/runtimets/testsuite_sqlpp.xml
index 0015fa6..11c9634 100644
--- a/asterixdb/asterix-app/src/test/resources/runtimets/testsuite_sqlpp.xml
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/testsuite_sqlpp.xml
@@ -12481,6 +12481,11 @@
       </compilation-unit>
     </test-case>
     <test-case FilePath="unnest">
+      <compilation-unit name="ASTERIXDB-2844_unnest_syntax">
+        <output-dir compare="Text">ASTERIXDB-2844_unnest_syntax</output-dir>
+      </compilation-unit>
+    </test-case>
+    <test-case FilePath="unnest">
       <compilation-unit name="left-outer-unnest">
         <output-dir compare="Text">left-outer-unnest</output-dir>
       </compilation-unit>
diff --git a/asterixdb/asterix-lang-sqlpp/src/main/javacc/SQLPP.jj b/asterixdb/asterix-lang-sqlpp/src/main/javacc/SQLPP.jj
index f4061e1..4c924a4 100644
--- a/asterixdb/asterix-lang-sqlpp/src/main/javacc/SQLPP.jj
+++ b/asterixdb/asterix-lang-sqlpp/src/main/javacc/SQLPP.jj
@@ -3499,12 +3499,12 @@
 UnnestClause UnnestClause(JoinType joinType) throws ParseException :
 {
     Token startToken = null;
-    Expression rightExpr;
-    VariableExpr rightVar;
+    Expression rightExpr = null;
+    VariableExpr rightVar = null;
     VariableExpr posVar = null;
 }
 {
-  (<UNNEST>|<CORRELATE>|<FLATTEN>) { startToken = token; } rightExpr = Expression() ((<AS>)? rightVar = Variable()) (<AT> posVar = Variable())?
+  (<UNNEST>|<CORRELATE>|<FLATTEN>) { startToken = token; } rightExpr = Expression() ((<AS>)? rightVar = Variable())? (<AT> posVar = Variable())?
   {
     if (rightVar == null) {
       rightVar = ExpressionToVariableUtil.getGeneratedVariable(rightExpr, true);