diff --git a/ng-verifier/src/request_processor.rs b/ng-verifier/src/request_processor.rs
index 8d92a07..1d2e797 100644
--- a/ng-verifier/src/request_processor.rs
+++ b/ng-verifier/src/request_processor.rs
@@ -294,11 +294,13 @@ impl Verifier {
                 ))
             }
             QueryResults::Boolean(b) => {
-                if b {
-                    AppResponse::V0(AppResponseV0::True)
-                } else {
-                    AppResponse::V0(AppResponseV0::False)
-                }
+                // FIX: Serialize boolean results as standard SPARQL JSON format
+                // instead of returning AppResponseV0::True/False
+                let serializer = QueryResultsSerializer::from_format(QueryResultsFormat::Json);
+                let result = serializer
+                    .serialize_boolean_to_write(Vec::new(), b)
+                    .map_err(|_| "QueryResult serializer error")?;
+                AppResponse::V0(AppResponseV0::QueryResult(result))
             }
             QueryResults::Graph(quads) => {
                 let mut results = vec![];