diff --git a/ssl-ca b/ssl-ca
index 38e21e91a6d4eb38cb20c3bd38864994989007e6..b02fa852015ad369b9c15e448bf457e4625bee3d 100755
--- a/ssl-ca
+++ b/ssl-ca
@@ -74,7 +74,7 @@ sign_key () {
         echo "Can't find key to sign."
         exit 1
     fi
-    csr="$(mktemp -t ssl-ca)"
+    csr="$(mktemp -t ssl-ca-XXXXXXXXX)"
     export domain="$1.$(basename $PWD)"
     openssl req \
         -key keys/$1 \