diff --git i/libmailutils/mailer/progmailer.c w/libmailutils/mailer/progmailer.c
index c61c917e3..a344d12df 100644
--- i/libmailutils/mailer/progmailer.c
+++ w/libmailutils/mailer/progmailer.c
@@ -45,7 +45,7 @@ struct _mu_progmailer
 {
   int fd;
   pid_t pid;
-  void (*sighandler)();
+  sighandler_t sighandler;
   char *command;
 };
 
