diff --git a/sci-chemistry/xcrysden/files/xcrysden-1.6.2-c23.patch b/sci-chemistry/xcrysden/files/xcrysden-1.6.2-c23.patch
new file mode 100644
index 0000000000..19924b4f09
--- /dev/null
+++ b/sci-chemistry/xcrysden/files/xcrysden-1.6.2-c23.patch
@@ -0,0 +1,12 @@
+https://bugs.gentoo.org/945707
+Fix conflicting types for fabs.
+--- a/C/xcBz.c
++++ b/C/xcBz.c
+@@ -1397,7 +1397,6 @@ static int
+ BzGetISS( int typ )
+ {
+   int imen[3 * BZ_MAXPOINTS], imin = 0;
+-  double fabs();
+   register int iss;
+   register double f, point;
+   register double tol = (double)(BZ_ISS - 1)/(double)BZ_ISS - (double)(BZ_ISS - 2)/(double)(BZ_ISS - 1);
diff --git a/sci-chemistry/xcrysden/xcrysden-1.6.2.ebuild b/sci-chemistry/xcrysden/xcrysden-1.6.2-r1.ebuild
similarity index 84%
rename from sci-chemistry/xcrysden/xcrysden-1.6.2.ebuild
rename to sci-chemistry/xcrysden/xcrysden-1.6.2-r1.ebuild
index 8d43bcf437..b1d099a318 100644
--- a/sci-chemistry/xcrysden/xcrysden-1.6.2.ebuild
+++ b/sci-chemistry/xcrysden/xcrysden-1.6.2-r1.ebuild
@@ -1,4 +1,4 @@
-# Copyright 1999-2022 Gentoo Authors
+# Copyright 1999-2025 Gentoo Authors
 # Distributed under the terms of the GNU General Public License v2
 
 EAPI=8
@@ -17,15 +17,17 @@ SLOT="0"
 
 KEYWORDS="~amd64"
 
-RDEPEND=">=x11-base/xorg-server-21.1.4
+RDEPEND="
+	>=x11-base/xorg-server-21.1.4
 	>=virtual/glu-9.0-r2
-	>=dev-lang/tcl-8.6.12
-	>=dev-lang/tk-8.6.12
+	>=dev-lang/tcl-8.6.12:=
+	>=dev-lang/tk-8.6.12:=
 	>=dev-tcltk/togl-2.0-r3
 	>=dev-tcltk/bwidget-1.9.14
-	>=media-libs/mesa-22.1.3
-	>=sci-libs/fftw-3.3.10"
-
+	media-libs/libglvnd[X]
+	sci-libs/fftw:3.0=
+	x11-libs/libX11
+"
 DEPEND="${RDEPEND}"
 
 PATCHES=(
@@ -33,6 +35,7 @@ PATCHES=(
 	"${FILESDIR}/${P}-LDFLAGS.patch"
 	"${FILESDIR}/${P}-Togl-lib.patch"
 	"${FILESDIR}/${P}-wrapper-paths.patch"
+	"${FILESDIR}/${P}-c23.patch"
 )
 
 src_prepare() {