diff --git a/sci-mathematics/gfan/files/gfan-0.5-gcc6.1-compat.patch b/sci-mathematics/gfan/files/gfan-0.5-gcc6.1-compat.patch
new file mode 100644
index 0000000000000..8479557b61bb8
--- /dev/null
+++ b/sci-mathematics/gfan/files/gfan-0.5-gcc6.1-compat.patch
@@ -0,0 +1,70 @@
+--- a/app_fiberpolytope.cpp
++++ b/app_fiberpolytope.cpp
+@@ -63,7 +63,7 @@
+ 
+ 	    /* If the vector configuration B does not have full rank then
+ 	       change coordinates. */
+-	    if(rank(B)!=B.getHeight())
++	    if(rank_(B)!=B.getHeight())
+ 	      {
+ 	        FieldMatrix M=integerMatrixToFieldMatrix(B,Q);
+ 	        M.reduce(false,true);//force integer operations - preserving volume
+@@ -83,7 +83,7 @@
+ 	    log1 debug<<"Done computing restricting cone\n";
+ 
+ 	    debug<<B.getRows();
+-	    debug<<int(rank(B));
++	    debug<<int(rank_(B));
+ 
+ 	    Triangulation2 t(B);
+ log1 debug<<"Computing initial triangulation\n";
+@@ -143,7 +143,7 @@
+ */
+     /* If the vector configuration A does not have full rank then
+        change coordinates. */
+-/*    if(rank(A)!=A.getHeight())
++/*    if(rank_(A)!=A.getHeight())
+       {
+ 	FieldMatrix M=integerMatrixToFieldMatrix(A,Q);
+ 	M.reduce(false,true);//force integer operations - preserving volume
+--- a/app_secondaryfan.cpp
++++ b/app_secondaryfan.cpp
+@@ -307,7 +307,7 @@
+ 
+     if(scaleOption.getValue())
+       {
+-	if(rank(A)!=A.getHeight())
++	if(rank_(A)!=A.getHeight())
+ 	  {
+ 	    cerr << "The vector configuration must have full rank in order to use the scale option.\n";
+ 	    assert(0);
+@@ -342,7 +342,7 @@
+ 
+     /* If the vector configuration A does not have full rank then
+        change coordinates. */
+-    if(rank(A)!=A.getHeight())
++    if(rank_(A)!=A.getHeight())
+       {
+ 	FieldMatrix M=integerMatrixToFieldMatrix(A,Q);
+ 	M.reduce(false,true);//force integer operations - preserving volume
+--- a/matrix.cpp
++++ b/matrix.cpp
+@@ -61,7 +61,7 @@
+ 
+ #include "linalg.h"
+ 
+-int rank(IntegerMatrix const &m)
++int rank_(IntegerMatrix const &m)
+ {
+   return integerMatrixToFieldMatrix(m,Q).rank();
+ }
+--- a/matrix.h
++++ b/matrix.h
+@@ -147,6 +147,6 @@
+ 
+ FloatMatrix integerToFloatMatrix(IntegerMatrix const &m);
+ IntegerVector flattenMatrix(IntegerMatrix const &m);
+-int rank(IntegerMatrix const &m);
++int rank_(IntegerMatrix const &m);
+ 
+ #endif
diff --git a/sci-mathematics/gfan/gfan-0.5-r1.ebuild b/sci-mathematics/gfan/gfan-0.5-r1.ebuild
new file mode 100644
index 0000000000000..aaf03c9d7ab9e
--- /dev/null
+++ b/sci-mathematics/gfan/gfan-0.5-r1.ebuild
@@ -0,0 +1,39 @@
+# Copyright 1999-2016 Gentoo Foundation
+# Distributed under the terms of the GNU General Public License v2
+# $Id$
+
+EAPI=6
+
+inherit eutils toolchain-funcs
+
+DESCRIPTION="computes Groebner fans and tropical varities"
+HOMEPAGE="http://www.math.tu-berlin.de/~jensen/software/gfan/gfan.html"
+SRC_URI="http://www.math.tu-berlin.de/~jensen/software/gfan/${PN}${PV}.tar.gz"
+
+LICENSE="GPL-2"
+SLOT="0"
+KEYWORDS="~amd64 ~arm ~x86 ~amd64-linux ~x86-linux"
+IUSE=""
+
+DEPEND="dev-libs/gmp[cxx]
+	sci-libs/cddlib"
+RDEPEND="${DEPEND}"
+
+S="${WORKDIR}/${PN}${PV}/"
+
+PATCHES=(
+	"${FILESDIR}/${P}-double-declare-fix.patch"
+	"${FILESDIR}/${P}-gcc6.1-compat.patch"
+	)
+
+src_prepare () {
+	default
+	sed -i -e "s/-O2/${CXXFLAGS}/" \
+		-e "/GPROFFLAG =/d" \
+		-e "s/g++/$(tc-getCXX)/" \
+		-e "s/\$(CCLINKER)/& \$(LDFLAGS)/" Makefile || die
+}
+
+src_install() {
+	emake PREFIX="${ED}/usr" install
+}