diff --git a/net-p2p/rtorrent/files/rtorrent-0.16.15-fix_riscv.patch b/net-p2p/rtorrent/files/rtorrent-0.16.15-fix_riscv.patch
new file mode 100644
index 0000000000000..0422f04cfeb7a
--- /dev/null
+++ b/net-p2p/rtorrent/files/rtorrent-0.16.15-fix_riscv.patch
@@ -0,0 +1,16 @@
+PR merged https://github.com/rakshasa/libtorrent/pull/778.patch
+see also https://bugs.gentoo.org/979046
+Subject: [PATCH] Add support for RISC-V
+--- a/scripts/common.m4
++++ b/scripts/common.m4
+@@ -118,6 +118,10 @@ AC_DEFUN([TORRENT_CHECK_CACHELINE], [
+             AC_MSG_RESULT([linux fallback enterprise 128 bytes])
+             AC_DEFINE([LT_SMP_CACHE_BYTES], 128, [Fallback 128-byte alignment for Linux enterprise hardware.])
+             ;;
++          riscv32*|riscv64*)
++            AC_MSG_RESULT([linux fallback RISC-V 64 bytes])
++            AC_DEFINE([LT_SMP_CACHE_BYTES], 64, [Fallback 64-byte alignment for Linux RISC-V hardware.])
++            ;;
+           *)
+             AC_MSG_RESULT([unrecognized CPU arch on Linux header fallback])
+             AC_MSG_FAILURE([Unrecognized CPU architecture ($host_cpu) on Linux fallback path. Aborting build.])
diff --git a/net-p2p/rtorrent/rtorrent-0.16.15.ebuild b/net-p2p/rtorrent/rtorrent-0.16.15.ebuild
index c80b12c6316e1..83071546070bc 100644
--- a/net-p2p/rtorrent/rtorrent-0.16.15.ebuild
+++ b/net-p2p/rtorrent/rtorrent-0.16.15.ebuild
@@ -46,6 +46,7 @@ BDEPEND="virtual/pkgconfig"
 
 PATCHES=(
 	"${FILESDIR}"/${PN}-0.16.13-cross_checks.patch
+	"${FILESDIR}"/${P}-fix_riscv.patch #979046
 )
 
 DOCS=( doc/rtorrent.rc )