diff --git a/sci-chemistry/gromacs/gromacs-2025.3.ebuild b/sci-chemistry/gromacs/gromacs-2025.3.ebuild
index 1f8ff67642678..5c89268a60e56 100644
--- a/sci-chemistry/gromacs/gromacs-2025.3.ebuild
+++ b/sci-chemistry/gromacs/gromacs-2025.3.ebuild
@@ -287,6 +287,8 @@ src_configure() {
 }
 
 src_compile() {
+	# fix sandbox violation bug #965866
+	addwrite /proc/mtrr
 	for x in ${GMX_DIRS}; do
 		einfo "Compiling for ${x} precision"
 		BUILD_DIR="${WORKDIR}/${P}_${x}"\
diff --git a/sci-chemistry/gromacs/gromacs-2025.4.ebuild b/sci-chemistry/gromacs/gromacs-2025.4.ebuild
index 92d289a8dc616..7afc8fd831a90 100644
--- a/sci-chemistry/gromacs/gromacs-2025.4.ebuild
+++ b/sci-chemistry/gromacs/gromacs-2025.4.ebuild
@@ -287,6 +287,8 @@ src_configure() {
 }
 
 src_compile() {
+	# fix sandbox violation bug #965866
+	addwrite /proc/mtrr
 	for x in ${GMX_DIRS}; do
 		einfo "Compiling for ${x} precision"
 		BUILD_DIR="${WORKDIR}/${P}_${x}"\
diff --git a/sci-chemistry/gromacs/gromacs-2025.9999.ebuild b/sci-chemistry/gromacs/gromacs-2025.9999.ebuild
index 92d289a8dc616..7afc8fd831a90 100644
--- a/sci-chemistry/gromacs/gromacs-2025.9999.ebuild
+++ b/sci-chemistry/gromacs/gromacs-2025.9999.ebuild
@@ -287,6 +287,8 @@ src_configure() {
 }
 
 src_compile() {
+	# fix sandbox violation bug #965866
+	addwrite /proc/mtrr
 	for x in ${GMX_DIRS}; do
 		einfo "Compiling for ${x} precision"
 		BUILD_DIR="${WORKDIR}/${P}_${x}"\
diff --git a/sci-chemistry/gromacs/gromacs-2026_rc.ebuild b/sci-chemistry/gromacs/gromacs-2026_rc.ebuild
index a66609b678900..a740c29ae5f92 100644
--- a/sci-chemistry/gromacs/gromacs-2026_rc.ebuild
+++ b/sci-chemistry/gromacs/gromacs-2026_rc.ebuild
@@ -288,6 +288,8 @@ src_configure() {
 }
 
 src_compile() {
+	# fix sandbox violation bug #965866
+	addwrite /proc/mtrr
 	for x in ${GMX_DIRS}; do
 		einfo "Compiling for ${x} precision"
 		BUILD_DIR="${WORKDIR}/${P}_${x}"\
diff --git a/sci-chemistry/gromacs/gromacs-9999.ebuild b/sci-chemistry/gromacs/gromacs-9999.ebuild
index a66609b678900..a740c29ae5f92 100644
--- a/sci-chemistry/gromacs/gromacs-9999.ebuild
+++ b/sci-chemistry/gromacs/gromacs-9999.ebuild
@@ -288,6 +288,8 @@ src_configure() {
 }
 
 src_compile() {
+	# fix sandbox violation bug #965866
+	addwrite /proc/mtrr
 	for x in ${GMX_DIRS}; do
 		einfo "Compiling for ${x} precision"
 		BUILD_DIR="${WORKDIR}/${P}_${x}"\