diff --git a/net-mail/mailutils/files/mailutils-3.19-format-security.patch b/net-mail/mailutils/files/mailutils-3.19-format-security.patch
new file mode 100644
index 0000000000000..2c49817a3b11d
--- /dev/null
+++ b/net-mail/mailutils/files/mailutils-3.19-format-security.patch
@@ -0,0 +1,36 @@
+From 9379ec9e25ae6bdbd3d6f5ef9930ac2176d2efe7 Mon Sep 17 00:00:00 2001
+From: Jordi Mallach <jordi@mallach.net>
+Date: Wed, 5 Mar 2025 12:13:06 +0100
+Subject: Fix missing format arguments for builds with -Wformat-security
+
+libmailutils/diag/debug.c (mu_debug_format_spec): Add missing "%s" to
+printf to avoid triggering -Wformat-security.
+---
+ libmailutils/diag/debug.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/libmailutils/diag/debug.c b/libmailutils/diag/debug.c
+index 2a1b52e..84c921a 100644
+--- a/libmailutils/diag/debug.c
++++ b/libmailutils/diag/debug.c
+@@ -511,7 +511,7 @@ mu_debug_format_spec (mu_stream_t str, const char *names, int flags)
+ 	{
+ 	  if (delim)
+ 	    {
+-	      rc = mu_stream_printf (str, delim);
++	      rc = mu_stream_printf (str, "%s", delim);
+ 	      if (rc)
+ 		break;
+ 	    }
+@@ -564,7 +564,7 @@ mu_debug_format_spec (mu_stream_t str, const char *names, int flags)
+ 	{
+ 	  if (delim)
+ 	    {
+-	      rc = mu_stream_printf (str, delim);
++	      rc = mu_stream_printf (str, "%s", delim);
+ 	      if (rc)
+ 		break;
+ 	    }
+-- 
+cgit v1.1
+
diff --git a/net-mail/mailutils/mailutils-3.19.ebuild b/net-mail/mailutils/mailutils-3.19.ebuild
index 2e1a21f4002f8..e00a959d23389 100644
--- a/net-mail/mailutils/mailutils-3.19.ebuild
+++ b/net-mail/mailutils/mailutils-3.19.ebuild
@@ -63,6 +63,7 @@ REQUIRED_USE="
 DOCS=( ABOUT-NLS AUTHORS COPYING COPYING.LESSER ChangeLog INSTALL NEWS README THANKS TODO )
 PATCHES=(
 	"${FILESDIR}"/${PN}-3.5-add-include.patch
+	"${FILESDIR}"/${PN}-3.19-format-security.patch
 )
 
 pkg_setup() {