diff --git a/modules/bitcoind.nix b/modules/bitcoind.nix
index 17b4cb4..5ee9363 100644
--- a/modules/bitcoind.nix
+++ b/modules/bitcoind.nix
@@ -122,12 +122,12 @@ in {
       };
 
       rpcuser = mkOption {
-          type = types.nullOr types.string;
+          type = types.nullOr types.str;
           default = null;
           description = "Username for JSON-RPC connections";
       };
       rpcpassword = mkOption {
-          type = types.nullOr types.string;
+          type = types.nullOr types.str;
           default = null;
           description = "Password for JSON-RPC connections";
       };
@@ -143,7 +143,7 @@ in {
         description = "Override the default port on which to listen for connections.";
       };
       proxy = mkOption {
-        type = types.nullOr types.string;
+        type = types.nullOr types.str;
         default = null;
         description = "Connect through SOCKS5 proxy";
       };
@@ -194,13 +194,13 @@ in {
         '';
       };
       zmqpubrawblock = mkOption {
-        type = types.nullOr types.string;
+        type = types.nullOr types.str;
         default = null;
         example = "tcp://127.0.0.1:28332";
         description = "ZMQ address for zmqpubrawblock notifications";
       };
       zmqpubrawtx = mkOption {
-        type = types.nullOr types.string;
+        type = types.nullOr types.str;
         default = null;
         example = "tcp://127.0.0.1:28333";
         description = "ZMQ address for zmqpubrawtx notifications";
diff --git a/modules/clightning.nix b/modules/clightning.nix
index dc47bb9..042187b 100644
--- a/modules/clightning.nix
+++ b/modules/clightning.nix
@@ -30,7 +30,7 @@ in {
       '';
     };
     proxy = mkOption {
-      type = types.nullOr types.string;
+      type = types.nullOr types.str;
       default = null;
       description = "Set a socks proxy to use to connect to Tor nodes (or for all connections if *always-use-proxy* is set)";
     };
@@ -42,12 +42,12 @@ in {
       '';
     };
     bind-addr = mkOption {
-      type = types.nullOr types.string;
+      type = types.nullOr types.str;
       default = null;
       description = "Set an IP address or UNIX domain socket to listen to";
     };
     bitcoin-rpcuser = mkOption {
-      type = types.string;
+      type = types.str;
       description = ''
         Bitcoin RPC user
       '';
diff --git a/modules/hardware-wallets.nix b/modules/hardware-wallets.nix
index 738804a..33d3a3c 100644
--- a/modules/hardware-wallets.nix
+++ b/modules/hardware-wallets.nix
@@ -23,7 +23,7 @@ in {
       '';
     };
     group = mkOption {
-      type = types.string;
+      type = types.str;
       default = "hardware-wallets";
       description = ''
         Group the hardware wallet udev rules apply to.
diff --git a/modules/lightning-charge.nix b/modules/lightning-charge.nix
index bd0e371..003a1b3 100644
--- a/modules/lightning-charge.nix
+++ b/modules/lightning-charge.nix
@@ -15,7 +15,7 @@ in {
       '';
     };
     clightning-datadir = mkOption {
-      type = types.string;
+      type = types.str;
       default = "/var/lib/clighting/";
       description = ''
         Data directory of the clightning service
diff --git a/modules/liquid.nix b/modules/liquid.nix
index 10ba050..968618d 100644
--- a/modules/liquid.nix
+++ b/modules/liquid.nix
@@ -111,12 +111,12 @@ in {
       };
 
       rpcuser = mkOption {
-          type = types.nullOr types.string;
+          type = types.nullOr types.str;
           default = null;
           description = "Username for JSON-RPC connections";
       };
       rpcpassword = mkOption {
-          type = types.nullOr types.string;
+          type = types.nullOr types.str;
           default = null;
           description = "Password for JSON-RPC connections";
       };
@@ -132,7 +132,7 @@ in {
         description = "Override the default port on which to listen for connections.";
       };
       proxy = mkOption {
-        type = types.nullOr types.string;
+        type = types.nullOr types.str;
         default = null;
         description = "Connect through SOCKS5 proxy";
       };
diff --git a/modules/recurring-donations.nix b/modules/recurring-donations.nix
index a4f46b0..1f9e491 100644
--- a/modules/recurring-donations.nix
+++ b/modules/recurring-donations.nix
@@ -61,7 +61,7 @@ in {
       '';
     };
     interval = mkOption {
-      type = types.string;
+      type = types.str;
       default = "Mon *-*-* 00:00:00";
       description = ''
         Schedules the donations. Default is weekly on Mon 00:00:00. See `man