diff --git a/global/post-tasks.d/015cosmos-trust b/global/post-tasks.d/015cosmos-trust
index f7d103c..dfd8a13 100755
--- a/global/post-tasks.d/015cosmos-trust
+++ b/global/post-tasks.d/015cosmos-trust
@@ -1,6 +1,6 @@
 #!/bin/sh
 
-if -z "$COSMOS_KEYS"; then
+if [ -z "$COSMOS_KEYS" ]; then
    COSMOS_KEYS=/etc/cosmos/keys
 fi