diff --git a/src/libguestfish.sh b/src/libguestfish.sh
index 8fcdf37b62faa98bd1ef8d23f4d2e4ef1259b4d4..a3e4abcb11bb9ea4b6b453d6f8fd11cd9a66613d 100755
--- a/src/libguestfish.sh
+++ b/src/libguestfish.sh
@@ -8,7 +8,7 @@ set -euo pipefail
 # We don't want to use libvirt for this, it inhibits debugging
 # shellcheck disable=SC2031
 export LIBGUESTFS_BACKEND=direct
-if [ "$COSA_NO_KVM" ];then
+if env|grep -q "^COSA_NO_KVM=";then
     export LIBGUESTFS_BACKEND_SETTINGS=force_tcg
 fi