diff --git a/games-board/gnugo/files/gnugo-3.9.1-format-security.patch b/games-board/gnugo/files/gnugo-3.9.1-format-security.patch
new file mode 100644
index 0000000000000..7828187c571df
--- /dev/null
+++ b/games-board/gnugo/files/gnugo-3.9.1-format-security.patch
@@ -0,0 +1,60 @@
+diff --git a/patterns/dfa.c b/patterns/dfa.c
+index 3689616..2d2f8c6 100644
+--- a/patterns/dfa.c
++++ b/patterns/dfa.c
+@@ -279,7 +279,7 @@ resize_dfa(dfa_t *pdfa, int max_states, int max_indexes)
+  * dump a dfa (debugging purpose).
+  */
+ 
+-static const char *line =
++static const char line[] =
+   "----------------------------------------------------\n";
+ 
+ void
+diff --git a/patterns/mkpat.c b/patterns/mkpat.c
+index 70a6964..5f1f1dd 100644
+--- a/patterns/mkpat.c
++++ b/patterns/mkpat.c
+@@ -1419,7 +1419,7 @@ generate_autohelper_code(int funcno, int number_of_params, int *labels)
+     /* A common case. Just use the labels as parameters. */
+     switch (number_of_params) {
+     case 0:
+-      code_pos += sprintf(code_pos, autohelper_functions[funcno].code);
++      code_pos += sprintf(code_pos, "%s", autohelper_functions[funcno].code);
+       break;
+     case 1:
+       code_pos += sprintf(code_pos, autohelper_functions[funcno].code,
+diff --git a/patterns/uncompress_fuseki.c b/patterns/uncompress_fuseki.c
+index 3290b05..c67a733 100644
+--- a/patterns/uncompress_fuseki.c
++++ b/patterns/uncompress_fuseki.c
+@@ -224,9 +224,9 @@ main(int argc, char *argv[])
+ 
+   assert(boardsize > 0);
+   if (boardsize > MAX_BOARD) {
+-    printf(output_strings[PREAMBLE]);
++    printf("%s", output_strings[PREAMBLE]);
+     printf(output_strings[HEADER], boardsize);
+-    printf(output_strings[FOOTER]);
++    printf("%s", output_strings[FOOTER]);
+     return EXIT_SUCCESS;
+   }
+   
+@@ -251,7 +251,7 @@ main(int argc, char *argv[])
+     board[k][boardsize + 1] = '|';
+   }
+ 
+-  printf(output_strings[PREAMBLE]);
++  printf("%s", output_strings[PREAMBLE]);
+   printf(output_strings[HEADER], boardsize);
+   
+ 
+@@ -308,7 +308,7 @@ main(int argc, char *argv[])
+   if (mode == C_OUTPUT)
+     write_pattern_c_code(NULL, board1d, NO_MOVE, 0, boardsize, -1);
+   
+-  printf(output_strings[FOOTER]);
++  printf("%s", output_strings[FOOTER]);
+ 
+   return EXIT_SUCCESS;
+ }
diff --git a/games-board/gnugo/gnugo-3.9.1-r2.ebuild b/games-board/gnugo/gnugo-3.9.1-r2.ebuild
new file mode 100644
index 0000000000000..b78c0ed865e06
--- /dev/null
+++ b/games-board/gnugo/gnugo-3.9.1-r2.ebuild
@@ -0,0 +1,30 @@
+# Copyright 1999-2018 Gentoo Foundation
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=6
+
+DESCRIPTION="A Go-playing program"
+HOMEPAGE="https://www.gnu.org/software/gnugo/devel.html"
+SRC_URI="mirror://gentoo/${P}.tar.gz"
+
+LICENSE="GPL-3"
+SLOT="0"
+KEYWORDS="~amd64 ~arm ~ppc64 ~x86 ~amd64-linux ~x86-linux ~ppc-macos"
+IUSE="readline"
+
+RDEPEND="
+	readline? ( sys-libs/readline:0= )
+	>=sys-libs/ncurses-5.2-r3:0=
+"
+DEPEND="${RDEPEND}"
+
+PATCHES=(
+	"${FILESDIR}"/${P}-invalid-move.patch
+	"${FILESDIR}"/${P}-format-security.patch
+)
+
+src_configure() {
+	econf \
+		$(use_with readline) \
+		--enable-cache-size=32
+}