diff --git a/beacon_node/http_metrics/src/lib.rs b/beacon_node/http_metrics/src/lib.rs
index e3238caae5..4837d513b5 100644
--- a/beacon_node/http_metrics/src/lib.rs
+++ b/beacon_node/http_metrics/src/lib.rs
@@ -116,6 +116,7 @@ pub fn serve<T: BeaconChainTypes>(
                     .unwrap_or_else(|e| {
                         Response::builder()
                             .status(500)
+                            .header("Content-Type", "text/plain")
                             .body(format!("Unable to gather metrics: {:?}", e))
                             .unwrap()
                     }),
diff --git a/validator_client/src/http_metrics/mod.rs b/validator_client/src/http_metrics/mod.rs
index 32227172ab..1e1c63640a 100644
--- a/validator_client/src/http_metrics/mod.rs
+++ b/validator_client/src/http_metrics/mod.rs
@@ -123,6 +123,7 @@ pub fn serve<T: EthSpec>(
                     .unwrap_or_else(|e| {
                         Response::builder()
                             .status(500)
+                            .header("Content-Type", "text/plain")
                             .body(format!("Unable to gather metrics: {:?}", e))
                             .unwrap()
                     }),