diff --git a/datafusion/physical-plan/src/union.rs b/datafusion/physical-plan/src/union.rs
index 2df85655e0b9..1cf22060b62a 100644
--- a/datafusion/physical-plan/src/union.rs
+++ b/datafusion/physical-plan/src/union.rs
@@ -475,8 +475,12 @@ fn union_schema(inputs: &[Arc<dyn ExecutionPlan>]) -> SchemaRef {
                 .filter_map(|input| {
                     if input.schema().fields().len() > i {
                         let field = input.schema().field(i).clone();
-                        let right_hand_metdata =
-                            inputs[1].schema().field(i).metadata().clone();
+                        let right_hand_metdata = inputs
+                            .get(1)
+                            .map(|right_input| {
+                                right_input.schema().field(i).metadata().clone()
+                            })
+                            .unwrap_or_default();
                         let mut metadata = field.metadata().clone();
                         metadata.extend(right_hand_metdata);
                         Some(field.with_metadata(metadata))