diff --git a/src/generic.rs b/src/generic.rs
index 56ed379..feddc72 100644
--- a/src/generic.rs
+++ b/src/generic.rs
@@ -865,6 +865,7 @@ pub trait ApiServiceProvider {
                 ResponseError {
                     status: response.status(),
                     message: err.to_string(),
+                    content_type: None,
                 }
             });
         }
diff --git a/src/timeseries/binary.rs b/src/timeseries/binary.rs
index 0ebea83..fee9834 100644
--- a/src/timeseries/binary.rs
+++ b/src/timeseries/binary.rs
@@ -737,6 +737,7 @@ fn unprocessable(message: String) -> ResponseError {
     ResponseError {
         status: StatusCode::UNPROCESSABLE_ENTITY,
         message,
+        content_type: None,
     }
 }
 
@@ -931,6 +932,7 @@ impl TimeSeriesService {
             return Err(ResponseError {
                 status: StatusCode::NOT_FOUND,
                 message: format!("Could not find following timeseries: {}", missing.join(", ")),
+                content_type: None,
             });
         }
         Ok(resolved)