diff --git a/base-notebook/start.sh b/base-notebook/start.sh
index 72a03418..760097a2 100755
--- a/base-notebook/start.sh
+++ b/base-notebook/start.sh
@@ -8,7 +8,7 @@ set -e
 # always log errors and warnings, but can be silenced by setting
 # JUPYTER_DOCKER_STACKS_QUIET.
 _log () {
-    if [[ "$*" == "ERROR:"* ]] || [[ "$*" == "WARNING:"* ]] || [[ "$JUPYTER_DOCKER_STACKS_QUIET" != "" ]]; then
+    if [[ "$*" == "ERROR:"* ]] || [[ "$*" == "WARNING:"* ]] || [[ "$JUPYTER_DOCKER_STACKS_QUIET" == "" ]]; then
         echo "$@"
     fi
 }