diff --git a/src/protopop3.h b/src/protopop3.h
index 25a36dd..22fd5f6 100644
--- a/src/protopop3.h
+++ b/src/protopop3.h
@@ -35,7 +35,7 @@ typedef struct protopop3_ctx {
 	unsigned int seen_command_count;
 } protopop3_ctx_t;
 
-int protopop3_validate(pxy_conn_ctx_t *, char *, size_t) NONNULL(1,2);
+int protopop3_validate(pxy_conn_ctx_t *, char *, size_t) NONNULL(1,2) WUNRES;
 
 protocol_t protopop3_setup(pxy_conn_ctx_t *) NONNULL(1);
 protocol_t protopop3s_setup(pxy_conn_ctx_t *) NONNULL(1);
diff --git a/src/protosmtp.h b/src/protosmtp.h
index 3feb0cf..d653d39 100644
--- a/src/protosmtp.h
+++ b/src/protosmtp.h
@@ -35,8 +35,8 @@ typedef struct protosmtp_ctx {
 	unsigned int seen_command_count;
 } protosmtp_ctx_t;
 
-int protosmtp_validate(pxy_conn_ctx_t *, char *, size_t) NONNULL(1,2);
-int protosmtp_validate_response(pxy_conn_ctx_t *, char *, size_t) NONNULL(1,2);
+int protosmtp_validate(pxy_conn_ctx_t *, char *, size_t) NONNULL(1,2) WUNRES;
+int protosmtp_validate_response(pxy_conn_ctx_t *, char *, size_t) NONNULL(1,2) WUNRES;
 
 protocol_t protosmtp_setup(pxy_conn_ctx_t *) NONNULL(1);
 protocol_t protosmtps_setup(pxy_conn_ctx_t *) NONNULL(1);
diff --git a/src/pxyconn.h b/src/pxyconn.h
index 7d9b6c8..a8bf919 100644
--- a/src/pxyconn.h
+++ b/src/pxyconn.h
@@ -68,7 +68,7 @@ typedef struct pxy_conn_desc pxy_conn_desc_t;
 typedef struct pxy_conn_child_ctx pxy_conn_child_ctx_t;
 
 typedef void (*init_conn_func_t)(evutil_socket_t,  short, void *);
-typedef int (*connect_func_t)(pxy_conn_ctx_t *);
+typedef int (*connect_func_t)(pxy_conn_ctx_t *) NONNULL(1) WUNRES;
 
 typedef void (*callback_func_t)(struct bufferevent *, void *);
 typedef void (*eventcb_func_t)(struct bufferevent *, short, void *);
@@ -76,18 +76,18 @@ typedef void (*eventcb_func_t)(struct bufferevent *, short, void *);
 typedef void (*bev_free_func_t)(struct bufferevent *, pxy_conn_ctx_t *);
 
 typedef void (*proto_free_func_t)(pxy_conn_ctx_t *);
-typedef int (*proto_validate_func_t)(pxy_conn_ctx_t *, char *, size_t);
+typedef int (*proto_validate_func_t)(pxy_conn_ctx_t *, char *, size_t) NONNULL(1,2) WUNRES;
 #ifndef WITHOUT_USERAUTH
 typedef void (*proto_classify_user_func_t)(pxy_conn_ctx_t *);
 #endif /* !WITHOUT_USERAUTH */
 
-typedef int (*child_connect_func_t)(pxy_conn_child_ctx_t *);
+typedef int (*child_connect_func_t)(pxy_conn_child_ctx_t *) NONNULL(1) WUNRES;
 typedef void (*child_proto_free_func_t)(pxy_conn_child_ctx_t *);
 
 typedef void (*set_watermark_func_t)(struct bufferevent *, pxy_conn_ctx_t *, struct bufferevent *);
 typedef void (*unset_watermark_func_t)(struct bufferevent *, pxy_conn_ctx_t *, pxy_conn_desc_t *);
 
-typedef filter_action_t * (*proto_filter_func_t)(pxy_conn_ctx_t *, filter_list_t *);
+typedef filter_action_t * (*proto_filter_func_t)(pxy_conn_ctx_t *, filter_list_t *) NONNULL(1,2) WUNRES;
 
 /*
  * Proxy connection context state, describes a proxy connection