diff --git a/grafana.nix b/grafana.nix
index be47848..385b95b 100644
--- a/grafana.nix
+++ b/grafana.nix
@@ -38,12 +38,12 @@
       exec 3>&1 >&2
       mkdir -p /var/lib/grafana
       if [ ! -s /var/lib/grafana/admin.pw ]; then
-        head -c 30 /dev/urandom | base64 > /var/lib/grafana/admin.pw
+        tr -dc _A-Z-a-z-0-9 </dev/urandom | head -c$\{1:-32} > /var/lib/grafana/admin.pw
         chmod 400 /var/lib/grafana/admin.pw
         chown grafana:grafana /var/lib/grafana/admin.pw
       fi
       if [ ! -s /var/lib/grafana/security.key ]; then
-        head -c 30 /dev/urandom | base64 > /var/lib/grafana/security.key
+        tr -dc _A-Z-a-z-0-9 </dev/urandom | head -c$\{1:-32} > /var/lib/grafana/security.key
         chmod 400 /var/lib/grafana/security.key
         chown grafana:grafana /var/lib/grafana/security.key
       fi
diff --git a/influxdb.nix b/influxdb.nix
index e8478f6..91c0434 100644
--- a/influxdb.nix
+++ b/influxdb.nix
@@ -49,15 +49,15 @@
         set -euo pipefail
         if [ ! -s /var/lib/influxdb/admin.pw ]; then
           INIT=1
-          head -c 30 /dev/urandom | base64 > /var/lib/influxdb/admin.pw
+          tr -dc _A-Z-a-z-0-9 </dev/urandom | head -c$\{1:-32} > /var/lib/influxdb/admin.pw
           chmod 400 /var/lib/influxdb/admin.pw
         fi
         if [ ! -s /var/lib/influxdb/knotendaten.pw ]; then
-          head -c 30 /dev/urandom | base64 > /var/lib/influxdb/knotendaten.pw
+          tr -dc _A-Z-a-z-0-9 </dev/urandom | head -c$\{1:-32} > /var/lib/influxdb/knotendaten.pw
           chmod 400 /var/lib/influxdb/knotendaten.pw
         fi
         if [ ! -s /var/lib/influxdb/grafana.pw ]; then
-          head -c 30 /dev/urandom | base64 > /var/lib/influxdb/grafana.pw
+          tr -dc _A-Z-a-z-0-9 </dev/urandom | head -c$\{1:-32} > /var/lib/influxdb/grafana.pw
           chmod 400 /var/lib/influxdb/grafana.pw
         fi
         until ${pkgs.curl}/bin/curl --connect-timeout 1 http://127.0.0.1:8086/ping; do