diff --git a/iso/builder/config/hooks/normal/9100-memtest.hook.binary b/iso/builder/config/hooks/normal/9100-memtest.hook.binary
new file mode 100755
index 0000000..4805d56
--- /dev/null
+++ b/iso/builder/config/hooks/normal/9100-memtest.hook.binary
@@ -0,0 +1,13 @@
+#!/bin/sh
+# Copy memtest86+ binaries from chroot /boot into the ISO boot directory
+# so GRUB can chainload them directly (they must be on the ISO filesystem,
+# not inside the squashfs).
+set -e
+
+for f in memtest86+x64.bin memtest86+x64.efi memtest86+ia32.bin memtest86+ia32.efi; do
+    src="chroot/boot/${f}"
+    if [ -f "${src}" ]; then
+        cp "${src}" "binary/boot/${f}"
+        echo "memtest: copied ${f} to binary/boot/"
+    fi
+done