diff --git a/bin/tests/system/mkeys/ns6/setup.sh b/bin/tests/system/mkeys/ns6/setup.sh
index 4cfeaa279f..fcbd28774f 100644
--- a/bin/tests/system/mkeys/ns6/setup.sh
+++ b/bin/tests/system/mkeys/ns6/setup.sh
@@ -24,7 +24,7 @@ unsupportedkey=Kunknown.+255+00000
 cp unsupported-managed.key "${unsupportedkey}.key"
 
 # root key
-rootkey=`cat ../ns1/managed.key`
+rootkey=$(cat ../ns1/managed.key)
 cp "../ns1/${rootkey}.key" .
 
 # Configure the resolving server with an initializing key.