diff --git a/sci-libs/mc/files/mc-1.5-missing-decl.patch b/sci-libs/mc/files/mc-1.5-missing-decl.patch
new file mode 100644
index 0000000000000..8c4b72af6e7ab
--- /dev/null
+++ b/sci-libs/mc/files/mc-1.5-missing-decl.patch
@@ -0,0 +1,13 @@
+Fix missing function declaration, so package could build with modern compilers
+https://bugs.gentoo.org/886457
+--- a/src/aprx/estim.c
++++ b/src/aprx/estim.c
+@@ -41,6 +41,8 @@
+     Bvec *u, Bvec *ud, Bvec *r);
+ VEXTERNC void Aprx_estFaceBump(Aprx *thee, int color,
+     Bvec *u, Bvec *ud, Bvec *r);
++VPUBLIC int Aprx_markRefineDorfler (Aprx *thee, double percentToRefine,
++    int color);
+ 
+ /*
+  * ***************************************************************************
diff --git a/sci-libs/mc/mc-1.5.ebuild b/sci-libs/mc/mc-1.5-r1.ebuild
similarity index 95%
rename from sci-libs/mc/mc-1.5.ebuild
rename to sci-libs/mc/mc-1.5-r1.ebuild
index 68c2785c64179..c7f303666e583 100644
--- a/sci-libs/mc/mc-1.5.ebuild
+++ b/sci-libs/mc/mc-1.5-r1.ebuild
@@ -1,7 +1,7 @@
-# Copyright 1999-2024 Gentoo Authors
+# Copyright 1999-2025 Gentoo Authors
 # Distributed under the terms of the GNU General Public License v2
 
-EAPI=7
+EAPI=8
 
 inherit autotools fortran-2
 
@@ -38,6 +38,7 @@ PATCHES=(
 	"${FILESDIR}"/1.4-multilib.patch
 	"${FILESDIR}"/1.4-doc.patch
 	"${FILESDIR}"/${P}-unbundle.patch
+	"${FILESDIR}"/${P}-missing-decl.patch
 )
 
 src_prepare() {