diff --git a/aggregator_api/src/models.rs b/aggregator_api/src/models.rs
index 5beb1792e..579e04cd9 100644
--- a/aggregator_api/src/models.rs
+++ b/aggregator_api/src/models.rs
@@ -23,7 +23,7 @@ pub(crate) enum AggregatorRole {
 
 #[derive(Serialize, PartialEq, Eq, Debug)]
 pub(crate) struct AggregatorApiConfig {
-    pub dap_versions: &'static [&'static str],
+    pub dap_version: &'static str,
     pub dap_url: Url,
     pub role: AggregatorRole,
     pub vdafs: Vec<SupportedVdaf>,
diff --git a/aggregator_api/src/routes.rs b/aggregator_api/src/routes.rs
index f333ff71f..bbd1ebbb4 100644
--- a/aggregator_api/src/routes.rs
+++ b/aggregator_api/src/routes.rs
@@ -33,7 +33,7 @@ pub(super) async fn get_config(
     State(config): State<Arc<Config>>,
 ) -> Json<AggregatorApiConfig> {
     Json(AggregatorApiConfig {
-        dap_versions: ["DAP-05"].as_slice(),
+        dap_version: "DAP-05",
         dap_url: config.public_dap_url.clone(),
         role: AggregatorRole::Either,
         vdafs: vec![
diff --git a/aggregator_api/src/tests.rs b/aggregator_api/src/tests.rs
index ccdd22bb5..bf5a0bec5 100644
--- a/aggregator_api/src/tests.rs
+++ b/aggregator_api/src/tests.rs
@@ -82,7 +82,7 @@ async fn get_config() {
             .await,
         Status::Ok,
         concat!(
-            r#"{"dap_versions":["DAP-05"],"dap_url":"https://dap.url/","role":"Either","vdafs":"#,
+            r#"{"dap_version":"DAP-05","dap_url":"https://dap.url/","role":"Either","vdafs":"#,
             r#"["Prio3Count","Prio3Sum","Prio3Histogram","Prio3CountVec","Prio3SumVec"],"#,
             r#""query_types":["TimeInterval","FixedSize"]}"#
         )