diff --git a/iso/builder/build.sh b/iso/builder/build.sh
index 673ad1e..fe2ba68 100755
--- a/iso/builder/build.sh
+++ b/iso/builder/build.sh
@@ -1688,7 +1688,12 @@ echo "=== building ISO (variant: ${BUILD_VARIANT}) ==="
 
 # Export for auto/config
 BEE_GPU_VENDOR_UPPER="$(echo "${BUILD_VARIANT}" | tr 'a-z-' 'A-Z_')"
-BEE_ISO_VOLUME="EASY_BEE_${BEE_GPU_VENDOR_UPPER}_V${ISO_VERSION_LABEL_TOKEN}"
+# ISO 9660 volume ID is limited to 32 characters; truncate the version token to fit.
+_vol_prefix="EASY_BEE_${BEE_GPU_VENDOR_UPPER}_V"
+_max_token=$(( 32 - ${#_vol_prefix} ))
+_vol_token="$(printf '%s' "${ISO_VERSION_LABEL_TOKEN}" | cut -c1-${_max_token})"
+BEE_ISO_VOLUME="${_vol_prefix}${_vol_token}"
+unset _vol_prefix _max_token _vol_token
 export BEE_GPU_VENDOR_UPPER BEE_ISO_VOLUME
 
 cd "${LB_DIR}"