p.patch

diff --git a/src/acme.rs b/src/acme.rs
index 6876326..d0d9dd5 100644
--- a/src/acme.rs
+++ b/src/acme.rs
@@ -18,7 +18,7 @@ use ngx::collections::Vec;
 use ngx::ngx_log_debug;
 use openssl::pkey::{PKey, PKeyRef, Private};
 use openssl::x509::{self, extension as x509_ext, X509Req};
-use types::{AccountStatus, ProblemCategory};
+use types::AccountStatus;
 
 use self::account_key::{AccountKey, AccountKeyError};
 use self::types::{AuthorizationStatus, ChallengeKind, ChallengeStatus, OrderStatus};
@@ -423,12 +423,7 @@ where
                 res = x;
                 order = deserialize_body(res.body())?;
             }
-            Err(RequestError::Protocol(problem))
-                if matches!(
-                    problem.category(),
-                    ProblemCategory::Order | ProblemCategory::Malformed
-                ) =>
-            {
+            Err(RequestError::Protocol(problem)) if problem.is_order_related() => {
                 return Err(problem.into())
             }
             _ => order.status = OrderStatus::Processing,
diff --git a/src/acme/error.rs b/src/acme/error.rs
index c7fd3c8..cff0d4b 100644
--- a/src/acme/error.rs
+++ b/src/acme/error.rs
@@ -10,7 +10,7 @@ use ngx::allocator::{unsize_box, Box};
 use thiserror::Error;
 
 use super::solvers::SolverError;
-use super::types::{self, Problem, ProblemCategory};
+use super::types::{self, Problem};
 use crate::net::http::HttpClientError;
 
 #[derive(Debug, Error)]
@@ -47,10 +47,7 @@ impl NewAccountError {
     pub fn is_invalid(&self) -> bool {
         match self {
             Self::ExternalAccount => true,
-            Self::Protocol(err) => matches!(
-                err.category(),
-                ProblemCategory::Account | ProblemCategory::Malformed
-            ),
+            Self::Protocol(err) => err.is_account_related(),
             Self::Status(_) => true,
             _ => false,
         }
@@ -105,10 +102,7 @@ impl From<RequestError> for NewCertificateError {
 impl NewCertificateError {
     pub fn is_invalid(&self) -> bool {
         match self {
-            Self::Protocol(err) => matches!(
-                err.category(),
-                ProblemCategory::Order | ProblemCategory::Malformed
-            ),
+            Self::Protocol(err) => err.is_order_related(),
             _ => false,
         }
     }
diff --git a/src/acme/types.rs b/src/acme/types.rs
index 7889e59..ef80f3b 100644
--- a/src/acme/types.rs
+++ b/src/acme/types.rs
@@ -355,6 +355,20 @@ impl Problem {
             _ => ProblemCategory::Other,
         }
     }
+
+    pub fn is_order_related(&self) -> bool {
+        matches!(
+            self.category(),
+            ProblemCategory::Order | ProblemCategory::Malformed
+        )
+    }
+
+    pub fn is_account_related(&self) -> bool {
+        matches!(
+            self.category(),
+            ProblemCategory::Account | ProblemCategory::Malformed
+        )
+    }
 }
 
 fn deserialize_vec_of_uri<'de, D>(deserializer: D) -> Result<Vec<Uri>, D::Error>