diff --git a/src/lib.rs b/src/lib.rs
index 4b8f67b..742a690 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -156,6 +156,9 @@ impl Response {
                 self.data.insert(key.to_string(), store);
             }
         } else {
+            if rec.len() != self.data.len() {
+                return Err("incorrect number of columns".to_string());
+            }
             for (key, value) in rec.iter() {
                 match self.data.get_mut(key) {
                     Some(data) => data.push(value.clone()),
@@ -244,6 +247,21 @@ mod responses {
             Err(_) => {}
         }
     }
+
+    #[test]
+    fn missing_field_error() {
+        let mut res = Response::new();
+        let mut rec1 = Record::new();
+        let mut rec2 = Record::new();
+        rec1.add("one", "one");
+        rec2.add("one", "one");
+        rec2.add("two", "two");
+        res.add(rec2).unwrap();
+        match res.add(rec1) {
+            Ok(_) => unreachable!("Should not accept additional value"),
+            Err(_) => {}
+        }
+    }
 }
 
 /// Support functions for Messages.