diff --git a/mail-mta/sendmail/files/sendmail-8.18.1-ctime.patch b/mail-mta/sendmail/files/sendmail-8.18.1-c23-ctime.patch
similarity index 100%
rename from mail-mta/sendmail/files/sendmail-8.18.1-ctime.patch
rename to mail-mta/sendmail/files/sendmail-8.18.1-c23-ctime.patch
diff --git a/mail-mta/sendmail/files/sendmail-8.18.1-c23-sm_strtoll.patch b/mail-mta/sendmail/files/sendmail-8.18.1-c23-sm_strtoll.patch
new file mode 100644
index 0000000000000..63d64b0164cec
--- /dev/null
+++ b/mail-mta/sendmail/files/sendmail-8.18.1-c23-sm_strtoll.patch
@@ -0,0 +1,29 @@
+Bug: https://bugs.gentoo.org/944460
+
+--- a/libsm/vfscanf.c
++++ b/libsm/vfscanf.c
+@@ -240,13 +240,13 @@
+ 			/* FALLTHROUGH */
+ 		  case 'd':
+ 			c = CT_INT;
+-			ccfn = (ULONGLONG_T (*)())sm_strtoll;
++			ccfn = (ULONGLONG_T (*)(const char *, char **, int))sm_strtoll;
+ 			base = 10;
+ 			break;
+ 
+ 		  case 'i':
+ 			c = CT_INT;
+-			ccfn = (ULONGLONG_T (*)())sm_strtoll;
++			ccfn = (ULONGLONG_T (*)(const char *, char **, int))sm_strtoll;
+ 			base = 0;
+ 			break;
+ 
+@@ -324,7 +324,7 @@
+ 			if (isupper(c))
+ 				flags |= LONG;
+ 			c = CT_INT;
+-			ccfn = (ULONGLONG_T (*)()) sm_strtoll;
++			ccfn = (ULONGLONG_T (*)(const char *, char **, int)) sm_strtoll;
+ 			base = 10;
+ 			break;
+ 		}
diff --git a/mail-mta/sendmail/sendmail-8.18.1.ebuild b/mail-mta/sendmail/sendmail-8.18.1.ebuild
index 95e367ed34524..211d7a748b698 100644
--- a/mail-mta/sendmail/sendmail-8.18.1.ebuild
+++ b/mail-mta/sendmail/sendmail-8.18.1.ebuild
@@ -66,7 +66,8 @@ PDEPEND="
 
 src_prepare() {
 	eapply "${FILESDIR}"/${PN}-8.16.1-build-system.patch
-	eapply "${FILESDIR}"/${PN}-8.18.1-ctime.patch
+	eapply "${FILESDIR}"/${PN}-8.18.1-c23-ctime.patch
+	eapply "${FILESDIR}"/${PN}-8.18.1-c23-sm_strtoll.patch
 	eapply -p0 "${FILESDIR}"/${PN}-delivered_hdr.patch
 	eapply_user